Component Out - How easy is it to accomplish?

[Trenton_net]

Hey Everyone,

Does anyone know how difficult it would be to get component out (NTSC) done on a PC Engine? I assume modifying a Tennokoe to do it would be pretty easy for someone with the requisite electronics skill? For that matter, has anyone here actually done this? :-)

[gzanelatto]

Hello! I´m new here, and I need some help on this thing too hehe.

Recently , I performed a mod for RGB on my PC Engine- it works fine. But now I got a problem with my rgb-vga converter and I want to play on my old tv. When I plug the composite output on the TV, I barely can see the images, only few shadows - I think its need some amp. I used the transistor BC337 to amplify my rgb cable, but I tried that one on the composite , without sucess. Any suggestion for amplify this thing?Thanks and sorry for my english ( brazillian here, hehe).

[Calpis]

Not easy, unless you use a premade transcoder board. But even then it might not "just work" since the PCE won't output TV ready RGB/the transcoder may be a garbage circuit. Not only does it take someone with the theory background, but also with time and expensive equipment too.

I say just use composite, or if you must, mod for S-video. Not only are they entirely adequate for the majority of games using the low resolution video modes, they are the only feasible methods to view games in their intended color (the raw 9-bit RGB gets hinted to 12-bit for better color choices/gamma/skin tone).

[Trenton_net]

Hrm... Sounds reasonable. I guess S-Video seems like a good compromise then. I kind of saw some pre-modded duos with component out and assumed it was a simple job. But even then, I'm sure composite will be just fine as I'm pretty used to it anyway.

I guess now I can worry about finding an easy way to dump PCE games. I guess the only off-the-shelf method is by using a Griffin? I think the Retrode can do it with an adapter, but I don't exactly have the skills to make one. It's a shame considering how many bad dumps there are. People don't seem to care about that as long as it runs in an emulator which is kind of sad.

[Lum]

Not easy, unless you use a premade transcoder board. But even then it might not "just work" since the PCE won't output TV ready RGB/the transcoder may be a garbage circuit. Not only does it take someone with the theory background, but also with time and expensive equipment too.

I say just use composite, or if you must, mod for S-video. Not only are they entirely adequate for the majority of games using the low resolution video modes, they are the only feasible methods to view games in their intended color (the raw 9-bit RGB gets hinted to 12-bit for better color choices/gamma/skin tone).

Huh. I thought PCE had fantastic RGB with a correct mod. Video signal clarity as distortion-free as the SNES Jr.

[keropi]

I have RGB modded my PCE using an RGB amp that my friend gtsamour made based on this schematic (http://i47.tinypic.com/2ed11s7.jpg), the picture quality is just awesome...

http://i125.photobucket.com/albums/p55/restqp/IMG00339-20120512-1439.jpg

not sure about the 9/12bit color "upscale" though, haven't noticed anything strange...

[Calpis]

I guess now I can worry about finding an easy way to dump PCE games. I guess the only off-the-shelf method is by using a Griffin? I think the Retrode can do it with an adapter, but I don't exactly have the skills to make one. It's a shame considering how many bad dumps there are. People don't seem to care about that as long as it runs in an emulator which is kind of sad.
Any copier can dump PCE games with an adapter, to me a SNES copier would be the obvious choice. It'd be really simple to make, just a PCE connector, SNES game and some wires.

Are there a lot of bad dumps? I don't have many HuCard games (maybe 8) but all of my dumps were in GoodPCE, and I've never had a game crash on me.


Huh. I thought PCE had fantastic RGB with a correct mod. Video signal clarity as distortion-free as the SNES Jr.
:dejection: When does anything not have "fantastic RGB"? RGB is the source of each subsequent video connection so it always has the best clarity, though in many cases the difference may be negligible, but in this case RGB doesn't have the correct COLOR which has nothing to do with clarity.


I have RGB modded my PCE using an RGB amp that my friend gtsamour made based on this schematic (http://i47.tinypic.com/2ed11s7.jpg), the picture quality is just awesome...
The PQ may be awesome (technical term) but that age-old circuit is crap.


not sure about the 9/12bit color "upscale" though, haven't noticed anything strange...
Upscale? It's not something you would notice unless you compared RGB and composite outputs side by side. Because your amplifier is not delivering the correct signal level to your display, nor is it properly terminated, it might be hard for you to be objective about this anyway.

[keropi]

Upscale? It's not something you would notice unless you compared RGB and composite outputs side by side. Because your amplifier is not delivering the correct signal level to your display, nor is it properly terminated, it might be hard for you to be objective about this anyway.

"Upscale" in lack of a better term to describe the 9->12bit transformation.... hence the quotation marks...
Please elaborate on the amp I am using and it's flaws , I don't mind improving/replacing it

[Lum]

:dejection: When does anything not have "fantastic RGB"? RGB is the source of each subsequent video connection so it always has the best clarity, though in many cases the difference may be negligible, but in this case RGB doesn't have the correct COLOR which has nothing to do with clarity.

Doesn't that depend on each specific game's developer intended?

[Bad_Ad84]

And which developer would be targeting a mode that doesnt exist on a retail console?

[keropi]

OK now I understand , it's color information we are destroying here... do the colors end up looking kinda washed up like on emulators with an RGB output?

[Lum]

And which developer would be targeting a mode that doesnt exist on a retail console?

RGB looking right could potentially impress trade shows and the press more than composite. I'm guessing it'd also make for easier color accuracy when porting to other consoles who have retail RGB.


OK now I understand , it's color information we are destroying here... do the colors end up looking kinda washed up like on emulators with an RGB output?

Not exactly "destroying". Rather you're seeing what the game programmers saw.

RGB is the original color information that games use for their palettes, and the console renders into usable graphics form. Encoding into formats like NTSC or PAL shifts color tones to some extent. An effect game makers had to consider when drawing their core RGB assets.

[keropi]

I just tried with composite and rgb on the same tv, they have 99% SAME color levels/intensity/"call it whatever you like" , only difference is that the RGB is way more sharper.

[Calpis]

Please elaborate on the amp I am using and it's flaws , I don't mind improving/replacing it
This is funny, why would you replace it when it clearly suits your needs? The problem with it is that 1) it's AC coupled instead of using a PNP for input 2) it doesn't have the required gain to deliver the expected level to the TV with termination 3) it doesn't have the proper output impedance expected by the TV 4) it uses a lot of current. The only good thing about it might be its linearity, but I'm not sure.


OK now I understand , it's color information we are destroying here... do the colors end up looking kinda washed up like on emulators with an RGB output?
Composite is lighter in general (due to RGB's linearity becoming non-linearity in the display). Also equally spaced RGB is very bold and ugly without a large bit depth, thankfully for the PCE 512 colors overcomes this (but not as well in RGB). This is because RGB isn't properly gamma-corrected (on the console) or properly converted to the sRGB colorspace (in emulators). You're supposed to gamma-correct all color and old consoles don't really do that, so the perceived light intensity from the display is not linear as intended. I'm not sure if the lookup table is specifically for gamma correction, but they changed colors for some reason, maybe personal preferences.


RGB looking right could potentially impress trade shows and the press more than composite. I'm guessing it'd also make for easier color accuracy when porting to other consoles who have retail RGB.
? OK.

RGB from one console isn't the same as RGB from another. They will have different bit depths and DAC linearity which means all colors must be rounded to the nearest available color anyway. Also different consoles have completely different palette capabilities so even if they had exactly the same color, the palettes will have to be changed entirely to fit the constraints of another console. Moot point because why would Hudson want PCE games to be portable? Obviously they wanted PCE to be ahead of the competition and that's why its video system is as unique as it is.


Not exactly "destroying". Rather you're seeing what the game programmers saw.
Game programmers back then worked on computer workstations with significantly less colors than the PCE, probably mostly PC-98s with 16 colors. When graphics were designed, guess where they were viewed.. on the PCE.. with composite.. probably on a 13-20" TV. Also many character (tile) editing and animation tools at that time actually ran on their respective console because there's no ambiguity over what it's going to look like.


I just tried with composite and rgb on the same tv, they have 99% SAME color levels/intensity/"call it whatever you like" , only difference is that the RGB is way more sharper.
It's notoriously difficult for humans to discern colors like that, side by side would be better. Since you say RGB is way sharper, then your TV has serious issues with composite. (But you should thank it for having AGC to fix video levels.) Most PCE video has a low enough resolution that the luma (which primarily defines sharpness/clarity to our eyes) completely fits into composite's allotted bandwidth with room to spare which also means that there's good chroma separation. On my TV PCE's composite looks sufficiently sharp, I can see well defined pixels and from memory dot crawl isn't noticeable thanks to the PCE's well designed encoder.

[gtsamour]

No difference I can see in color between RGB and composite either. And in my humble opinion, if most people can't see the color difference between the two (RGB also way better in sharpness unless your tv has a serious issues with RGB), who cares what anyone else says...

And yes, I can see pixels in composite too (in my 55'' LCD tv.... LOL) but not in my trinitron 21'' crt lets be serious...

[APE]

While the usage of transistors makes for a decent amp I would imagine this would be applicable:
http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb_new.htm

Looks good IMO but that doesn't make it a good amp to use.



:dejection: When does anything not have "fantastic RGB"? RGB is the source of each subsequent video connection so it always has the best clarity, though in many cases the difference may be negligible, but in this case RGB doesn't have the correct COLOR which has nothing to do with clarity.

When you wire your N64 without an amp and everything is too dark to be of any real use. PEBKAC obviously.

[Calpis]

No difference I can see in color between RGB and composite either.
You have a PCE hooked up to two identical displays side by side? The long moment where your display flips A/V inputs is long enough for you to not see the difference. By its nature composite doesn't have exactly the same color as RGB so this is really far fetched.


While the usage of transistors makes for a decent amp I would imagine this would be applicable:
http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb_new.htm

Looks good IMO but that doesn't make it a good amp to use.
The THS7314 would be a very good amp to use, it'll have much better performance than any discrete amp design you can find online.

[gtsamour]

You have a PCE hooked up to two identical displays side by side? The long moment where your display flips A/V inputs is long enough for you to not see the difference. By its nature composite doesn't have exactly the same color as RGB so this is really far fetched.


The THS7314 would be a very good amp to use, it'll have much better performance than any discrete amp design you can find online.

I really don't need and don't care much to compare side by side. As long as i can't see any difference big enough to stand out and make a memorable impression, its same enough for me and almost everybody. Exactly the same can't be since composite smudges the picture a bit, RGB picture on the other hand is crystal clear. I have compared RGB picture from an actual PCE to an emulator picture of the same game and its indistinguishable.

As for the pixel you mentioned before, noway you can see it on a CRT tv using composite. With RGB you can see pixels even on low quality pictures taken of a tv screen http://www.pcenginefx.com/forums/index.php?topic=9299.0 Do you really think that a composite picture can be compared with the RGB shown on these pictures ?

The THS7314 could be a tolerable solution, not the best IMO since to get the best RGB picture you need to use Sync instead of the crappy composite signal which can cause checkerboard patterns on the RGB screen. Sync signal needs to be amplified too thus you need an extra amplifier to do that which the THS7314 does not provide.

[Lum]

From pictures I've seen... Blue looks better in composite. Red looks better in RGB.

Which doesn't seem like much surprise. NTSC is infamous for hideous reds IIRC.

[gtsamour]

From pictures I've seen... Blue looks better in composite. Red looks better in RGB.

Which doesn't seem like much surprise. NTSC is infamous for hideous reds IIRC.

I have most of PCE consoles, both US and JAP versions and seen the picture in each and everyone of them on both composite and modded for RGB (using the above x4 (RGB + Sync) amplifier made using the schematic which IMO is superior to the THS7314 solution) , TG16, PCE, Core II, Supergrafx, PCE DUO, DUO R... you name it.... and I'm talking about CRT tv which is the tv these consoles were meant to be played on and not some LCD that apply digital filters on the picture making composite "only look" sharp which in reality is very far from that.

Trust me... everything looks WAY better in RGB, there's absolutely no measure of comparisson to composite, none.

[Lum]

PCE isn't really where composite shows its uses best. Most composite-related effects are found on Genesis, SNES has a few as well.

[gtsamour]

Well if you're talking about the effects composite produces like checkerboard or vertical lines on the RGB pictures, yes Im aware that on Genesis for example (and master system) it can cause a lot of these. But I've seen similar effects on a premodded DUO-R Ι got recently that used composite instead of Sync. Checkerboard pattens were obvious.

If you want the best RGB picture possibe, always use Sync instead of the messy composite.

[Calpis]

As for the pixel you mentioned before, noway you can see it on a CRT tv using composite.
Maybe your TV can't. This isn't a limitation of composite video. With a good signal you can even see pixel edges through RF modulation... PCE video for the most part has a bandwidth of 2.68 MHz, and just about every TV has a luma bandwidth of over 3 MHz. Since luma is more influential by far to the PQ, and luma isn't filtered to below the PCE's bandwidth, luma directly follows the PCE's pixel clock the same as RGB. Technically unfiltered computer pixels have very high frequency content which allows very sharp pixel boundaries, composite loses a lot of this, S-video retains most of it. With RGB it's limited by the bandwidth of your transmission line and display. For PCE it doesn't really matter, you can still see the edges of many pixels.

The place where composite mainly fails in games is because often the I component of chroma dips down into luma causing artifacts. I'm not sure exactly how the PCE filters chroma, but it's possible there is very little interference at all at the cost of color bandwidth, basically only in patterns of alternating black and white pixels. By using S-video you are completely free of the artifacts, making the only clarity issues the low chroma bandwidth which your eyes are not supposed to be able to discern.


Do you really think that a composite picture can be compared with the RGB shown on these pictures ?
Those pictures? Yes, more or less. BTW, you should use less JPEG compression when showing off your PQ :P


The THS7314 could be a tolerable solution, not the best IMO since to get the best RGB picture you need to use Sync instead of the crappy composite signal. Sync signal needs to be amplified too thus you need an extra amplifier to do that which the THS7314 does not provide.
Your opinion is somewhat misinformed, the sync in composite video is identical to composite sync, it's essentially a digital signal. Is composite sync more pure? Yes, because composite video has is composite sync with some other stuff at higher frequencies. Does it make any bit of difference? Not really, composite video is more than adequate at carrying the low frequency sync signal to achieve a stable raster... The source of sync has absolutely nothing to do with picture quality, the only signals responsible for that are R, G and B.

That said I agree that regular composite sync is better, because many displays such as arcade monitors are not equipped to handle composite video.

No you don't need to amplify sync. You need to provide the display with the desired level however, and TVs desire ~0.3 V into 75 ohms. This can be done from the logic level sync output which on the PCE will be around 5V... With a few resistors you can attenuate 5V to 0.6 V with 75 ohm output which will divide to 0.3V with the display's 75 ohm termination resistor. This is the proper way to do it, and if you're concerned about current or ESD you can buffer the signal. Since termination is hardly an issue on a slow sync signal you could even have a high impedance sync output without problems, this requires only a single resistor and will definitely fall within the current sourcing capabilities of any logic chip.

Technically your amplifiers aren't really amplifiers in the normal sense (voltage gain) at all, they're current amplifiers (lossy voltage buffers). They are achieving approximately the desired signal level by brute force, meaning they take 4x or more current to deliver the same signal to the TV, without the benefits of termination. It only looks adequate because the PCE has such low bandwidth video.

[Lum]

In theory composite video isn't too bad for what it is. In real-world usage scenarios, it often turns out that way. Some consoles and TVs have bad encoding or decoding. Either may display artifacts.

Using RGB a console already has, is an easier way to get around said artifacts than trying to replace the console's encoder and/or TV's decoder. And less expensive than buying a high end XRGB type device.

[gzanelatto]

Any suggestion to amplify my composite signal? Just direct wiring you can´t get any normal image on CRT.

[Calpis]

LCD that apply digital filters on the picture making composite "only look" sharp which in reality is very far from that.
Truth be told your CRT is probably applying digital filters too, not just on composite for the 3D combfilter but possibly also on your RGB in order for it to provide a stable menu overlay. Can you get a menu overlay in RGB mode? If so it probably is digitizing the picture (albeit with low latency).

I'm under the impression that almost all mid-high end TVs from the 90s onwards actually sample their video to operate on it in the digital domain. They sample it at 13.5 MHz http://en.wikipedia.org/wiki/Rec._601
If your TV does this to RGB you get little of RGB's benefits over S-video because the bandwidth is limited to below 6.75 MHz (DVD quality) whereas most truely analog arcade RGB monitors will have bandwidths of 15 MHz and up. Now if you couple game RGB that's properly terminated to a 60 MHz CRT you'd see true sharpness and the actual benefits of RGB. You can actually do this easily at home with a nice VGA monitor and custom emulator...

This is why I can't take RGB nuts too seriously, everyone thinks their setup is so great but if they understood what was really happening to their signals through their mods and encoder/transcoder/upscanner/scanline inserter etc signal chains some heads would explode.


In theory composite video isn't too bad for what it is.
Composite video is great, it allowed cable TV to be possible. It isn't however great for computers/games, but for the most part it's sufficient. It would have been cool if all consoles only output RGB and everyone made optional universal RGB RF/composite/S-video/YPbPr modulators in order for consoles to be cheaper and all provide RGB, but things didn't turn out like that.


Any suggestion to amplify my composite signal? Just direct wiring you can´t get any normal image on CRT.
Uhh? You mean the original white RF PCE? The best solution would be to recreate the composite video amplifier from the CoreGrafx but that's kind of complicated. If you're talking about using composite output from a CoreGrafx, IFU, DUO etc then you have a bad composite video input.

[Lum]

This is why I can't take RGB nuts too seriously, everyone thinks their setup is so great but if they understood what was really happening to their signals through their mods and encoder/transcoder/upscanner/scanline inserter etc signal chains some heads would explode.

The end justifies the means. Video display at the stage of visible light from the CRT's front glass is what matters. Not that it's "correct" from an electric engineering view point.
Most home users seeking maximum quality, intend to improve their game experience, rather than write science reports on the signal chain.

[gtsamour]

The end justifies the means. Video display at the stage of visible light from the CRT's front glass is what matters. Not that it's "correct" from an electric engineering view point.
Most home users seeking maximum quality, intend to improve their game experience, rather than write science reports on the signal chain.

Exactly!!! At the end of the day, results on the screen is what matters and by my observations, RGB is by far the best option to get the best results. With RGB I get a clear colourful and normal looking picture having the same colors as an emulator and thats what everybody wants from a 20+ year old console. Composite may be providing a relatively good picture compared to RF but according to my observations on more than one tv set, it just doesn't hold a candle to RGB.
And probably this is why everyone on www.pcenginefx.com (http://www.pcenginefx.com/) which is the best place to get technical info on the PCE, considers the amplifier I used, the best solution to get an excellent RGB picture out of this console. Afterall as I said, the result is what counts.

Digital filters applied by LCD sets make the graphics look unreal and not at all as they were meant to look on the glass crt screen. So whatever "digital filter" a crt is appliying (if any), the outcome on an LCD is weird and on a CRT its not. Again, only results matter most and not theory.

Compare composite and RGB on an LCD and they might look almost identical after all the digital filtering. Truth is, they aren't, compare on a crt 4:3 and you'll see the difference with your own eyes.

Sync signal (or composite sync if you preffer it) needs amplification, many monitors or RGB capable european tv sets, have trouble displaying a stable picture if you use sync straight out of the PCE's chip pin.
My set can display OK with or without amplification on sync but I've noticed small differences in clarity and colours so I go with amplifying the Sync which is also what is recomended on the www.pcenginefx.com (http://www.pcenginefx.com) forum.

[Lum]

Well that doesn't mean you want to just toss any old idea together.

My crt's component input gets screen rolling(!) if Sega Genesis video transcoded from RGB gets too strong or whatever. Most noticeable in Sonic 3, especially large areas of white like its file select screen and the Ice Cap Zone snowboard intro.

[gtsamour]

Neither a too strong nor a too weak signal is good. This is why I'm always using the amplifier I gave a link before in all my modifications for RGB. Actually the schematics for it are taken from the PCEngine 1988 Japanese Book (there is a name for it in Japanese but I can't type it, sorry). This amp is supposed to be specificaly designed to give the best possible RGB out on a PCEngine, taking the appropriate signals either from the chip's pins or from the expansion port.

[keropi]

yeah IIRC in the part that the transistor legend is pasted over it actually had the NEC logo and the page number from said book...

[Calpis]

The end justifies the means. Video display at the stage of visible light from the CRT's front glass is what matters. Not that it's "correct" from an electric engineering view point.
Most home users seeking maximum quality, intend to improve their game experience, rather than write science reports on the signal chain.
What's "correct" isn't an opinion, it's a measurable fact. TV's are designed and calibrated to accept very specific signals. When you send a TV bad video and are satisfied with the outcome, it's because either you have low or peculiar standards or the TV is extremely forgiving of bad video signals. If you try the same shit on another monitor that EXPECTS good video, such as a lot of professional equipment, if it tolerates it at all it will show you the exact mangled video you give it.


Exactly!!! At the end of the day, results on the screen is what matters and by my observations, RGB is by far the best option to get the best results.
That's great, but it's also an opinion... 1) You don't have an end-all TV, and it appears to be a PAL/multi-system TV instead of a native NTSC one 2) we can't reproduce your results at home.


With RGB I get a clear colourful and normal looking picture having the same colors as an emulator and thats what everybody wants from a 20+ year old console.
You can't speak for everybody. If that's what people wanted then why are so many emulators implementing NTSC filters these days? Why were hqx, Sai, Super Eagle etc algorithms so popular 10 years ago? Everyone has different tastes.


Composite may be providing a relatively good picture compared to RF but according to my observations on more than one tv set, it just doesn't hold a candle to RGB.
Speak for your TV. How about taking pictures of your PCE in composite so we can see the difference on your TV at least?


And probably this is why everyone on www.pcenginefx.com (http://www.pcenginefx.com/) which is the best place to get technical info on the PCE, considers the amplifier I used, the best solution to get an excellent RGB picture out of this console.
The best place to get technical info on the PCE? Really? lol That's a fan/collector's forum where there are a handful of technical people if that, and it's highly unlikely any of them are also electrical engineers with emphasis in video allowing them to pass judgement on the circuit.

People use that circuit because they don't know better. GameSX published it like 10 years ago, so its been around the block. How can you claim it's the best solution if you admittedly don't know electronics? None of my problems with it are being refuted...


Compare composite and RGB on an LCD and they might look almost identical after all the digital filtering. Truth is, they aren't, compare on a crt 4:3 and you'll see the difference with your own eyes.
I never once brought up LCD, I'm only talking about CRT. Again you're speaking from personal, possibly limited, experiences. State that you can see the difference on your equipment with your eyes, not a blanket statement for everyone.


Sync signal (or composite sync if you preffer it) needs amplification, many monitors or RGB capable european tv sets, have trouble displaying a stable picture if you use sync straight out of the PCE's chip pin.
*sigh* I already addressed this. It doesn't, you're doing it wrong. Sync starts as a LOGIC signal, it's not meant to drive a transmission line. That doesn't mean it needs amplification, it means you need to not load it so much. The TV's 75 ohm load is incredibly big for a LOGIC output. Also TVs cannot be expected to accept a logic level sync signal.


Neither a too strong nor a too weak signal is good. This is why I'm always using the amplifier I gave a link before in all my modifications for RGB.
Again TVs have a DEFINED signal "strength", which I have previously referred to as "level". This is a fact, whether you want to believe so or not.


Actually the schematics for it are taken from the PCEngine 1988 Japanese Book
PC Engine no Subete. Just because it was published in a mook doesn't make it any less of an amateur circuit, sorry to say. If you still want to believe it's the best possible amp, go for it, I've done my part.


yeah IIRC in the part that the transistor legend is pasted over it actually had the NEC logo and the page number from said book...
Wha? NEC logo? 1) The book is not by NEC (or Hudson) 2) the transistor is an extremely common generic transistor in Japan, it can be replaced by any small signal NPN, 3) the transistor is made by Toshiba.

OT: If you check out the datasheet you'll even see that Toshiba intends it for audio frequency applications (150+ times slower than video), this happens to coincide with the amplifier circuit being talked about which passes for an audio buffer stage.

[gtsamour]

That's great, but it's also an opinion... 1) You don't have an end-all TV, and it appears to be a PAL/multi-system TV instead of a native NTSC one 2) we can't reproduce your results at home.
Well I guess it is... so is yours. 1) My TVs (all 5 of them, some crt some lcd) except one, support all systems including NTSC and are also able to display both composite and RGB so I know the difference not only on the PCE but on other consoles as well. RGB is obviously superior on all of them 2) Of course you can't, last time I checked TVs in the states don't support RGB, but ofcourse there are crt monitors... so I guess your experience with RGB is limited.



You can't speak for everybody. If that's what people wanted then why are so many emulators implementing NTSC filters these days? Why were hqx, Sai, Super Eagle etc algorithms so popular 10 years ago? Everyone has different tastes. Emulators are a different thing and people might like experimenting with filters to see how they look like. Playing on the real thing is a different matter though and when someone does, he wants the real thing or as close as he can get to that. I believe I speak for most of the people.



Speak for your TV. How about taking pictures of your PCE in composite so we can see the difference on your TV at least? Why don't you? You're the one supporting something that goes against something thats common knowledge and opinion. Convince us. There are a lot of pictures on the internet showing the same frame of a game on both composite and RGB already and guess which one looks better. Knock yourself out http://www.youtube.com/watch?v=qvl2whFM04s
http://www.chrismcovell.com/gotRGB/screenshots.html



People use that circuit because they don't know better. GameSX published it like 10 years ago, so its been around the block. How can you claim it's the best solution if you admittedly don't know electronics? None of my problems with it are being refuted... For a simple reason... it works and it gives great picture that I (and many many others using it) have confirmed with my own eyes. The schematics were not published by GameSX by the way, just passed on.




PC Engine no Subete. Just because it was published in a mook doesn't make it any less of an amateur circuit, sorry to say. If you still want to believe it's the best possible amp, go for it, I've done my part.
At least it was published somewhere and most certainly if it works well or not has been confirmed by hundreds. Which is more than I can say for your claims.

[Bad_Ad84]

Id suggest not arguing with Calpis unless you are going to use technical facts rather than opinion.

You are using knowledge assumed, just because something appears to work. Caplis is using electronics knowledge and facts, you are just using "because it works", which isnt really valid.

Lots of things work, but that doesnt mean they are the correct way of doing things. Which is his point. You have seem to have no reply other than "Well, it works!".

Dont get me wrong, Calpis can come across arrogant and/or confrontational - but he rarely just throws around opinion as fact. His arguments have lots of facts and working electronics theory to back him up. He is worth listening to.

[gtsamour]

1st: I can argue with whomever I want.
2nd: Knowledge on a topic doesn't make someone necessarily right on everything that has to do with that.
3rd: Composite is inferior to RGB by a lot and this is common knowledge for decades. No Calpis's expertese can convince me or anyone else having vision otherwise just by throwing some numbers or blaming the tv set for not displaying composite right.
4th: "Well it works" is what matters. We're playing games here, not designing a satellite thats gonna go into space. Im not saying his theory is necessarily wrong, in practise things are different than in theory some (or most) of the times.
At least I have seen and compared the results this amp provides in real life and have an opinion about it, he hasn't (obviously).

[Trenton_net]

1st: I can argue with whomever I want.
2nd: Knowledge on a topic doesn't make someone necessarily right on everything that has to do with that.
3rd: Composite is inferior to RGB by a lot and this is common knowledge for decades. No Calpis's expertese can convince me or anyone else having vision otherwise just by throwing some numbers or blaming the tv set for not displaying composite right.
4th: "Well it works" is what matters. We're playing games here, not designing a satellite thats gonna go into space. Im not saying his theory is necessarily wrong, in practise things are different than in theory some (or most) of the times.
At least I have seen and compared the results this amp provides in real life and have an opinion about it, he hasn't (obviously).

1) Sure.
2) Ok.
3) Arguable. Define "A lot" and what is considered "inferior" by most people. There are pros and cons for both sides of the camp.
4) No way. It works to punch a guy in the face and rob him of his money too, but that doesn't mean it's right. Or the correct way to go about getting money. Sure, we're talking about video games (which in life is somewhat trivial) but it doesn't make something any less right or wrong.

[gtsamour]

A lot is this http://www.chrismcovell.com/gotRGB/screenshots.html Distinguishable difference in quality beyond any doubt, thats a lot.
I would like to hear some of these pros of composite and some of the cons of RGB compared to composite. I understand that its somewhat more difficult to have rgb in the US compared to Europe since your tvs don't support rgb but try to be objective on some matters. Overall rgb is much better and thats why a lot of people have their consoles modded for rgb.

[Lum]

Id suggest not arguing with Calpis unless you are going to use technical facts rather than opinion.

You are using knowledge assumed, just because something appears to work. Caplis is using electronics knowledge and facts, you are just using "because it works", which isnt really valid.

Lots of things work, but that doesnt mean they are the correct way of doing things. Which is his point. You have seem to have no reply other than "Well, it works!".

Dont get me wrong, Calpis can come across arrogant and/or confrontational - but he rarely just throws around opinion as fact. His arguments have lots of facts and working electronics theory to back him up. He is worth listening to.

He isn't so much wrong, as making the situation more complicated than it needs to be. Many of us don't own professional video equipment with the kinds of tolerances he's talking about. Or TVs/consoles whose composite encoding & decoding is good enough to seriously contend against RGB in our own setups. Not that it's impossible. My N64 composite on CRT looks good. (of course it's not yet RGB modded to make any comparison)

[Calpis]

Well I guess it is... so is yours.
It's not my opinion that composite is identical to RGB, I've already outlined my points. I've been playing devil's advocate because I have a problem with "by far" and "best" being thrown around.


Emulators are a different thing and people might like experimenting with filters to see how they look like. Playing on the real thing is a different matter though and when someone does, he wants the real thing or as close as he can get to that. I believe I speak for most of the people.
As close as "he" can get to what? Do people who play on emulators not have a valid opinion? There are more people playing emulators today than there are people playing real consoles. Many aren't experimenting, they will continually play with either HQ scaling, artifact or softening algorithms. As for console players, they don't have the same options available to them so who's to say they wouldn't use HQ scaling if they could? I'm under the impression that for both groups the vast majority of people don't care how the game is viewed as long as it's playable.


Why don't you? You're the one supporting something that goes against something thats common knowledge and opinion. Convince us. There are a lot of pictures on the internet showing the same frame of a game on both composite and RGB already and guess which one looks better. Knock yourself out http://www.youtube.com/watch?v=qvl2whFM04s
http://www.chrismcovell.com/gotRGB/screenshots.html
All of my PCE are in storage, but I might...

I think these are pretty good examples of composite, especially the video. And that's despite it being such a small monitor (13" or 15"?) having a very poor dot pitch that approaches the pixel width, and the last comparison shots being slightly biased towards RGB because composite is blooming. Look at the System Card licensing text at the bottom of the screen, the font's strokes are 1 pixel wide. You don't think the pixel edges are clearly defined? The only problem I see is somewhat significant chroma interference up close, but 1) separating chroma is the display's job and I don't think the monitor has a 2D much less 3D comb filter, it might not have a comb filter at all, and 2) S-video completely alleviates this problem.


For a simple reason... it works and it gives great picture that I (and many many others using it) have confirmed with my own eyes.
Your eyes can't confirm that your amplifier is drawing more current than the HuCard, or predict that your regulator will melt the PCE's enclosure, until it happens.

Do you similarly use your ears to judge audio amplifier performance?


The schematics were not published by GameSX by the way, just passed on.
Posting anything to the internet is publishing it. Maybe somebody submitted it to the site but I don't see any photo/contribution credits and many GameSX articles are derived from similar Japanese material such as Backup Technique so it didn't seem so unreasonable for it to be "original" content. I fail to see how this matters, GameSX has had it up at least 8 years and GameSX practically brought region/controller/RGB-modding to the internet so AFAIK it's the go-to site for such things and where plenty of people would have come across it.


At least it was published somewhere and most certainly if it works well or not has been confirmed by hundreds. Which is more than I can say for your claims.
Which claims? AFAIK my claims refer to TV standards which are "confirmed" by the BILLIONS of TV sets produced worldwide since the dawn of color NTSC.


Composite is inferior to RGB by a lot and this is common knowledge for decades. No Calpis's expertese can convince me or anyone else having vision otherwise just by throwing some numbers or blaming the tv set for not displaying composite right.
As it's been said over and over again, "by a lot" is completely subjective. I never said composite is BETTER than RGB, that's an illogical statement. In the PCE's case however one might argue it due to the color hinting, and the fact that RGB requires modding the console... With the FC/NES on the other hand I would definitely argue that composite is better for compatibility and aesthetic reasons, and I have many times on this board even.


At least I have seen and compared the results this amp provides in real life and have an opinion about it, he hasn't (obviously).
I'm not going to install said amp to confirm what I already know. I can tell you unquestionably that the THS integrated amp is better in every way and I'm not going to test that "theory" either. (Personally I don't enjoy maiming consoles.)

This is a hunch, but from your statements I'm afraid you're drawing a parallel between video and audio signals. I understand why you would do this, but to do so is incorrect, it's a vast oversimplification of a complex system.


He isn't so much wrong, as making the situation more complicated than it needs to be.
I think the generalizations in this thread aren't depicting the situation complicated enough, so that's why I'm still here. It's important to see multiple sides of a story and some sides few people will tell. By doing so I hope I can convince a few people to take the red pill.

BTW, I'm not really dealing with the theoretical here.

[Lum]

There is one fatal flaw we're overlooking. PCE does not adhere to the NTSC standard as written to begin with. Television broadcasts (the original intent for NTSC) were interlaced, not progressive.

[Calpis]

I'm not sure where you're going with that. Analog TVs can't tell the difference between progressive and interlaced. Technically progressive-scan is the "default" type of raster and interlaced video is a video signal trick, not the other way around as people sometimes say. The consequence of progressive scanning on a CRT is that the same phosphors are hit at 60 Hz instead of at 30 Hz, so maybe each line glows brighter since they are intended to decay for 1/30 s (they are chosen for interlaced video), but then all the blank "scanlines" possibly averages this out spatially, I'm not sure. The consequence of progressive scanning on a non-CRT is that the DSP may get confused.

There's no difference electrically between progressive and interlaced. All consoles should be outputting NTSC compliant video signals (technically even RGB and PAL signals are derived from NTSC "IRE" units) for the best signal integrity, many are slightly off however for petty cost saving measures or because they were poorly engineered hence numerous PCB/chip revisions. Also game video has been historically deemed low quality so engineers probably think the signal integrity cuts are justified and will go unnoticed.

[Lum]

Hmm I have no technical experience to give much opinion there. But it appears that line of debate would lead us off-track from the topic's purpose. Which is determining what circuit would get the sharpest cleanest image from PCE. Clearly defined object edges are not subjective. Geometric shapes are defined standards with no room for negotiation or interpretation. A square is a square, etc.

[Calpis]

Are you talking about sharpest image in theory or out of stock PCE hardware? There is no such thing as a perfect amplifier, but you could for example stick a modern 300 MHz HDTV amplifier in a PCE. This is overkill, but it will replicate the signal very very precisely, almost as if the amplifier wasn't there at all. If someone recreated part of the PCE's logic in a FPGA, it's possible to actually output pixels SHARPER than the stock hardware because modern logic is much faster, and the output stage can be designed to better standards. Unless you're using a HD CRT it makes little difference though because even slow logic has very fast transition times, much faster than the bandwidth of a typical CRT can capture.

When I first replied to this thread I had forgotten about the THS amp, that is the obvious solution. There are possibly a few comparable integrated amps out there with higher bandwidth, but 8.5 MHz is pretty good for PCE. For N64 on the other hand you probably want more like 25 MHz (an EDTV amplifier).

Also believe it or not geometric shapes in games are not definitive. Game consoles use different pixel clocks which define the "pixel aspect ratio". Unless a game uses a PRECISELY square pixel clock (which no consoles do) it's impossible to get absolutely perfect geometry on a perfectly calibrated display. The PCE has rectangular pixels so the game designer has to make an oval shape for a circle to appear on the screen.

Interlacing vs progressive doesn't affect it since progressive fills up the same screen real estate vertically.

[gzanelatto]

Uhh? You mean the original white RF PCE? The best solution would be to recreate the composite video amplifier from the CoreGrafx but that's kind of complicated. If you're talking about using composite output from a CoreGrafx, IFU, DUO etc then you have a bad composite video input.


Yes, my PCE version is the original japanese one, with RF output only. How complex is to recreate that amplifier? Is there a kind of guide? I tried searching over the internet, and only found the rgb mod that I´ve already performed... ( and I want to play now because I had no prevision of getting another rgb for next months anyway ... )

Thanks!

[Lum]

Within the realm of PCE's core hardware. Cleaning up its video with amplifiers or encoders is OK.
It'd likely be excessive effort relative to benefit, to do things like develop a new PPU.

[gtsamour]

I think I'm gonna pass on the rest of Calpis's hypochondriac BS here... so long...

[Lum]

Yeah don't try to digest the whole thing at once. Keep his overall idea in mind, in case you run into trouble. Video errors are frustrating...

[gtsamour]

Overall idea? As I said... hypochondriac BS

[Lum]

The part about signal levels correct for your TV. Remember what I said about Genesis with RGB-to-component on my CRT.

[gtsamour]

Yes the screen rolling you mentioned. But I never had any problems with signal levels and I've made many mods on many kinds of consoles, ever on retro computers and I'm always testing them on 5 sets to confirm they work on all of them.

If the console has RGB out by factory default like the Megadrive I, or MasterSystem I, etc then make a correct scart cable and it is bound to work.
If it doesn't then make a mod and a correct cable and it will probably work.

[Bad_Ad84]

But I never had any problems with signal levels and I've made many mods on many kinds of consoles, ever on retro computers and I'm always testing them on 5 sets to confirm they work on all of them.

How do you know? Testing it on 5 tv's doesnt mean its right. It just means its working.

And everything works until it breaks. Look at all the people who killed their dreamcasts by leaving the 12v connected "because it worked" (but eventually killed the console).

Just because something seems to be working, doesnt mean its not doing damage to the console or the TV. Or that the TV is being very forgiving and displaying it correctly despite it being wrong.

[Lum]

What would you do to avoid PCE video distortion then?

[Bad_Ad84]

I have never seen/owned a PCE - but that isnt my point. I am not commenting on how to do something, just that his reasoning for arguing is completely flawed.

I also do not claim to know a great deal about analog electronics.

However, I am not the one arguing with someone that does, with the only retort being "but it works!" by testing it on 5 tvs, rather than actually investigating signal levels with an oscilloscope .

[Lum]

I guess so. I don't know what signal levels are correct for my TVs. Without that info, an oscilloscope will only tell part of the story.

[Bad_Ad84]

And Calpis does, which is kinda the point in all this.

[Lum]

Hence why I didn't say he was wrong. Not necessarily always being immediately relevant, if even coherent, doesn't make one incorrect. I have enough experience to know when something wrong is displayed on screen. Eyes tell me that.

[Bad_Ad84]

Your eyes cant measure current - which calpis has already said. Your eyes cant tell you if the circuit is correct.

This is the point, people are arguing the circuit is fine because it looks OK. That is wrong.

[keropi]

So almost-back-on-topic , one could use a THS for RGB amplification and use sync as-is?

[Lum]

Your eyes cant measure current - which calpis has already said. Your eyes cant tell you if the circuit is correct.

This is the point, people are arguing the circuit is fine because it looks OK. That is wrong.

Ah yes. More newbie friendly put that way.

[gtsamour]

No we are not just argueing that the cirquit is fine just because it looks OK on screen. Its right because besides looking OK onscreen, it was also designed and published for this purpose (PCEngine RGB) by people with more knowledge on these things than me or most people.
I didn't come up with this cirquit by myself and support that since its working it is OK.
Its been published on this 1988 japanese book and it is proven to work all these years till now, so I guess it was designed to output the correct currents and they were confirmed on the real thing before going ahead publishing it.

So forgive me if i dont give a F about someone else's postings in a forum playing expert on everything.

Bottomline, it may be an "amateur cirquit" but its good enough for PCEngine.

[Lum]

Yeah next time you run into difficulty, you'll be able to refer back to this topic for clues how to fix it.

[APE]

No we are not just argueing that the cirquit is fine just because it looks OK on screen. Its right because besides looking OK onscreen, it was also designed and published for this purpose (PCEngine RGB) by people with more knowledge on these things than me or most people.
I didn't come up with this cirquit by myself and support that since its working it is OK.
Its been published on this 1988 japanese book and it is proven to work all these years till now, so I guess it was designed to output the correct currents and they were confirmed on the real thing before going ahead publishing it.

So forgive me if i dont give a F about someone else's postings in a forum playing expert on everything.

Bottomline, it may be an "amateur cirquit" but its good enough for PCEngine.

What is "give a F"?

It may look fine on screen for your displays but that doesn't mean dick. I've used one circuit for S-Video only to find on another TV of a similar model it doesn't work at all. If it was published in 1988 it stands to reason that something better has come along. Since you're clearly interested in what is better (or else you wouldn't be bothering with RGB in the first place) logically you should be interested in using a better circuit for a better picture (subjectively speaking). Instead you're defending a circuit in the same way people defend their favorite sport team or favorite beer - fanboy style that is.

You don't appear to have a vested interest in the circuit beyond it is what is used in your hardware. My guess is that you fervently believe in the circuit and can't handle someone with the knowledge telling you that what you believe may be incorrect - that is that the circuit, while appearing to produce good results on screen, isn't the end all be all you felt it was. People enjoy being right and will defend something they believe in strongly even if it is clear they may very well be incorrect.

And it is beyond obvious you have no expertise in this realm. Simply telling the world it is "good enough" is not the makings of a well thought out opinion on a circuit nor does it lend any credibility to the circuit actually being good. I can drive a screw into a wall using a hammer but that doesn't make it a nail.


So almost-back-on-topic , one could use a THS for RGB amplification and use sync as-is?

It would seem so. I can tell you that it works pretty good for the N64 though with Calpis suggesting 25mhz I'll be looking into that for kicks.

[gtsamour]

Its "give a fuck",

I don't have any personal gain to defend this amp and yes I'm not an electronic expert cirquit design wise but other people that are and with which I've spoken with and discussed relative matters, consider it a good option that gets the job done.

So no, I'm not just going to ditch it just because someone thats obviously hypochondriac says its an amateur cirquit just because it doesn't satisfy his obsessive compulsive disorder for perfectionism. Amateur cirquit means dick as long as its not flawed in some serious fucked up way and this one isn't. It could be better yes, but Its not flawed.

[keropi]

[...]
It would seem so. I can tell you that it works pretty good for the N64 though with Calpis suggesting 25mhz I'll be looking into that for kicks.

I was thinking since yesterday that I read this to open a thread about the n64 amp , my pre-modded system has a simplified resistor/transistor amp IIRC and I am not that excited with it's performance... it's time to try something else I think...

[Lum]

Its "give a fuck",

I don't have any personal gain to defend this amp and yes I'm not an electronic expert cirquit design wise but other people that are and with which I've spoken with and discussed relative matters, consider it a good option that gets the job done.

So no, I'm not just going to ditch it just because someone thats obviously hypochondriac says its an amateur cirquit just because it doesn't satisfy his obsessive compulsive disorder for perfectionism. Amateur cirquit means dick as long as its not flawed in some serious fucked up way and this one isn't. It could be better yes, but Its not flawed.

Not something to worry about now. It's simply knowledge, that may or may not become useful to you later. Never know. Your next tv could hate the mods.

[gtsamour]

Doubt it

[Calpis]

Unless a game uses a PRECISELY square pixel clock (which no consoles do)
I forgot about digital video, so this isn't quite true, consoles with HDMI have perfectly square pixels.


Yes, my PCE version is the original japanese one, with RF output only. How complex is to recreate that amplifier? Is there a kind of guide?
Thanks!
http://www.assemblergames.com/forums/showthread.php?35063-Adding-S-Video-to-TG-16-PCE-Duo

http://i1216.photobucket.com/albums/dd379/PCGenjin/cvbs.png?t=1295176022

Thank tomaitheous but note that the resistor values are probably off so it might not be much use.


The TV is being very forgiving and displaying it correctly despite it being wrong.
This is most likely the case with a lot of mods, my TV can handle exceptionally bad signals I created with very little experience.


What would you do to avoid PCE video distortion then?
What kind of distortion?


I don't know what signal levels are correct for my TVs
All TVs from the same region use the same signal levels! Plus the difference between NTSC, NTSC-J and PAL is very very slight. RGB can be thought of as 3x NTSC-J signals with chroma removed and sync moved to a separate wire.


So almost-back-on-topic , one could use a THS for RGB amplification and use sync as-is?
You can't use sync as-is. I think it's a logic level signal but I'm not sure. Assuming it is, you can try using it through a 1.2k resistor which will divide it to the appropriate TV level. The VCE (chip you solder to) may have an issue supplying the meager 4 mA of current, so if you want to be safe you can buffer the signal with a 74AHCT1G126 (or probably any 5V logic buffer) then through the 1.2K.


it was also designed and published for this purpose (PCEngine RGB) by people with more knowledge on these things than me or most people.
5 of the 7 components are arranged into a simple textbook amplifier like this: http://tronixstuff.files.wordpress.com/2010/07/1txamp.jpg

Of the 2 remaining components the 75 ohm R choice suggests a misunderstanding of the circuit, and the 10/300 ohm R looks like tweak to get it working.


I don't have any personal gain to defend this amp
Even after calling it "the best"?


obsessive compulsive disorder for perfectionism
This is silly, I play via composite 90% of the time.


Amateur cirquit means dick as long as its not flawed in some serious fucked up way and this one isn't. It could be better yes, but Its not flawed.
It has flaws, they just happen to be invisible. If this amplifier were used as an RGB "amp" for another console there's a high chance of the 10 uF capacitor exploding. Does that count?

[Bad_Ad84]

Why not just use Composite Video as the sync source?

Assuming you are connecting it to a RGB enabled TV (rather than a monitor or something) thats a perfectly valid source of sync and should be correct for the TV to use as is.

Also means if you connect to a TV without a RGB enabled scart socket - it would fall back to composite, which is exactly how scart is supposed to work.

use the THS amp + composite video

Or am I missing something?

[Lum]

"I forgot about digital video, so this isn't quite true, consoles with HDMI have perfectly square pixels."

Old consoles deserve the next best thing. Clearly defined pixels may look nicer than fuzziness.

"This is most likely the case with a lot of mods, my TV can handle exceptionally bad signals I created with very little experience."

Right. What works for a user and they find safe, should be understood as just that. Nothing more or less. "wrong" doesn't mean unusable, intolerable, or even mediocre. It can be a very entertaining graphics experience.
Us who use our consoles to enjoy are ultimately best served in the real world by how games look.
Either way past a certain point the "right" way begins to have diminishing returns. Eventually one hits quality roadblocks in the console's and/or TV's design.

"What kind of distortion?"

The distortion on setups where composite/etc gets blatant significantly inferior overall sharpness to RGB/etc.

"This is silly, I play via composite 90% of the time."

Many people do. It's often a damn travesty how games look for a large portion of them, relative to what a game's artists drew. Of course for those who don't care/know any better it isn't much of an issue to them.
If anything I regret learning as much as I have. Blissful child ignorance seeing blurred 80s visuals on a CRT without it mattering, was an experience I'll never get back.

[Bad_Ad84]

Some games are designed to look correct over composite, rather than RGB. They are intentionally using the effects of composite.

NES for example. If you RGB mod it, some games do not like right.

[Lum]

Some games are designed to look correct over composite, rather than RGB. They are intentionally using the effects of composite.

NES for example. If you RGB mod it, some games do not like right.

Yeah part of the problem. One can't have things both ways. Full screen blur means objects that don't use the effects suffer.

An intelligent blurring solution could in theory be more ideal. Except doing that to peak effectiveness, involves tailoring a filter for specific games.

[gtsamour]

Why not just use Composite Video as the sync source?

Assuming you are connecting it to a RGB enabled TV (rather than a monitor or something) thats a perfectly valid source of sync and should be correct for the TV to use as is.

Also means if you connect to a TV without a RGB enabled scart socket - it would fall back to composite, which is exactly how scart is supposed to work.

use the THS amp + composite video

Or am I missing something?

It works but using composite instead of composite sync can cause stable checkerboard or vertical lines patterns onscreen. This is particularly visible on Genesis/Megadrive, Mastersystem, NeoGeo and maybe others I haven't come across yet. I've also seen this happening on the DUO-R PCEngine. If you use composite sync you get none of these.


5 of the 7 components are arranged into a simple textbook amplifier like this: http://tronixstuff.files.wordpress.com/2010/07/1txamp.jpg

Of the 2 remaining components the 75 ohm R choice suggests a misunderstanding of the circuit, and the 10/300 ohm R looks like tweak to get it working.
So what. A simple textbook amplifier with modifications can't be suited to work on a pcengine?



Even after calling it "the best"?
I call it the best value for money solution. Simple and small enough that gets the job done on an old console giving excellent visual results.



This is silly, I play via composite 90% of the time.
I meant cirquit design wise. You're being too "perfect" when in practise you'll get very little (if at all) out of it, specially in pcengine's case. Maybe you could use your "perfectionism" to solve the jailbar issue on the pcengine that is visible on both composite and rgb but more on the later due to better sharpness. That would be perfect since no one has done it so far.



It has flaws, they just happen to be invisible. If this amplifier were used as an RGB "amp" for another console there's a high chance of the 10 uF capacitor exploding. Does that count?
No it doesn't. This amp was published as a pcengine specific rgb amp and I never said otherwise.

[Bad_Ad84]

I have only experienced that on the N64 - all other consoles have been fine (as its the way scart is designed to be used, to fall back to composite).

[gtsamour]

I have only experienced that on the N64 - all other consoles have been fine (as its the way scart is designed to be used, to fall back to composite).

If you only used them on crt then yes I agree with you, they are not visible. Use them on an LCD and you'll see them, can't miss them, they are particularly visible on solid backgrounds like the sky in wonderboy in monsterland for example. With composite sync you get clear picture on both types of tvs. Possibly the digital processing an lcd does on the signal makes the extra data in composite that normaly are useless for RGB, appear like this. http://i918.photobucket.com/albums/ad30/gorgyrip/IMG_1533.jpg

[keropi]

^ I have experienced it on both my md1 and sms2 machines... when I switched to c-sync the rainbow/checker/wavy artifacts completely disappeared...


edit:

will this work? (provided you feed +5v / GND on the appropriate pins)

http://i46.tinypic.com/209r3sx.jpg

Also what is "output enable input" pin on the 74AHCT1G126GW (datasheet link (http://www.datasheetcatalog.org/datasheet/philips/74AHCT1G126GW.pdf)) , do we need it?

[APE]

I
So no, I'm not just going to ditch it just because someone thats obviously hypochondriac...

I don't think that word means what you think it means. At the very least in this context I don't see how Calpis is a hypochondriac.

[gtsamour]

Hypochondriac is someone that is making a big deal over nothing and exagerating. Trust me I know what it means, afterall it is a Greek word.

[Calpis]

Old consoles deserve the next best thing. Clearly defined pixels may look nicer than fuzziness.
Huh? They can't have it, they're analog. If you recreated the consoles to give them HDMI out, then you'd have to scale the image horizontally to make it look right with square pixels. If you didn't and it were "pixel perfect", video would be scrunched horizontally like most emulators were until recently.

Here is what square pixels looks like without scaling: http://img201.imageshack.us/img201/8552/pc20kid2022028pc20genji.gif

Here's how square pixels would look w/ fake scanlines (according to Ootake):
http://img267.imageshack.us/img267/8175/pcg2.th.png (http://img267.imageshack.us/img267/8175/pcg2.png)

Here's how square pixels would look w/ horizontal stretching to approximate the pixel aspect the PCE is using for this screen, as viewed on a TV (according to Ootake... which is inaccurate in this regard, but you get the idea, it's slightly wider):
http://img40.imageshack.us/img40/3633/pcg2b.th.png (http://img40.imageshack.us/img40/3633/pcg2b.png)


"wrong" doesn't mean unusable, intolerable, or even mediocre. It can be a very entertaining graphics experience.
(How is this STILL being miscommunicated??) Wrong shouldn't have air quotes, it literally is wrong, and yes it does mean intolerable and mediocre at least. It means that you're lucky if a bad circuit is usable on 1, 2 or 10 TVs because it might not be usable on the 11th. If it doesn't work on the 11th do you call the TV bad? You shouldn't because it's not the TV's fault, it just isn't forgiving of bad signals. A properly constructed circuit will deliver a working signal on ALL working TVs. That's the difference. Doing things the right way isn't a diminishing return until you're shipping many thousands of units and you know exactly where you're skimping. For a modder the costs of a few components are trivial. People are more likely to exercise the law of diminishing returns on their brain energy expended to learn to do things the right way. That's fine when people skimp on their private projects and maybe even offer the circuit to other people for their private projects, but it's a problem when people relentlessly promote and defend and install kludge circuits.


The distortion on setups where composite/etc gets blatant significantly inferior overall sharpness to RGB/etc.
You asked for it so here's a big reply:

"blatant significantly inferior"? It doesn't, look at the comparison video posted earlier. Most people have no objection to composite's sharpness, they object to the video artifacts (which actually is a kind of modulation distortion), and the artifacts can be improved by using a better comb filter, or removed entirely by using S-video.

Sharpness is dependent on bandwidth, the more high frequency content is allowed to pass, the sharper pixels may transition. RGB obviously has the most bandwidth, but S-video was designed to give you the same viewing experience at a significant reduction in chroma bandwidth, and it succeeds with more or less color bleeding. Composite is S-video transmitted on a single wire instead of two; to achieve this luma (which is responsible for the majority of sharpness we see) must also go through a significant reduction in bandwidth so both can fit into the frequency spectrum of a broadcast TV channel (only 6 MHz for NTSC). That said, I don't think the luma bandwidth allotted for composite is insufficient for viewing most PCE(/FC/MKIII/SFC) video... I don't think it's even insufficient for viewing MD (/lowres PS/SAT/N64), you can still make out pixel boundaries with a clean signal.

It's "high resolution" games (480i and up) where you finally cannot make out pixels via composite, they're all blurred together. Even RGB might not have clearly defined pixels in 480i video modes because the TV might not have the bandwidth for it. Also small TVs with poor dot pitches begin to influence the pixels we see. For sharp game pixels we need a very fine dot pitch.

Ironically most current gen games have such complicated graphics that they imitate natural video, the kind composite was designed to compress, so they look really good over composite (apart from small text being illegible and other bad design choices).

This is quite off-topic and complicated but really important: sharp pixels only exist synthetically. They are created by extremely high frequency components present in a signal output from a fast DAC without a "reconstruction filter". In some applications like audio a reconstruction filter is an absolute necessity because you're severely distorting the signal through aliasing without one. Video is the same way if you are viewing natural video like a live TV show or movie on DVD, the goal is to accurately reproduce the original information that was captured by the camera, not distort objects the camera captured by displaying them as distinguishable pixels. Unnatural video from games and computer applications are made up in the digital world so there is no analog smoothness to recreate/aliasing to suppress, (old) video games that aren't meant to imitate real life or playback natural video don't have reconstruction filters and that's why they may have beautifully sharp pixels wherever bandwidth permits. Even though the PCE's main 5.37 MHz pixel clock only theoretically has a bandwidth of 5.37 MHz / 2, the fast transition speed of the PCE's DAC is creating frequency components with significant energy (because it isn't suppressed by a reconstruction filter) up to probably around 100 MHz. When you have a crappy TV with a RGB bandwidth of 5 MHz your pixels aren't very sharp, you're missing 95% of the possible sharpness. A sharp signal requires at least 3x the fundamental frequency (5.37 MHz / 2) at minimum, or preferably 5x, 7x or 9x which would come to under 30 MHz... If you had a HD CRT with over 100 MHz bandwidth you would actually be able to accurately view the PCE's *full* sharpness, but only if you use correct video transmission circuits as I have been advocating. Bad circuits lead to unintentional filtering which means that you may not get the full sharpness that your display is capable of.




relative to what a game's artists drew.
Back in 8-bit days artists designed game characters on graph paper and entered them pixel by pixel, I think the artists knew what they were getting into because they had to design around the constraints of RF lol. (Remember the original PCE was RF only.) Today we're still doing injustice to artists' conception since we have limited texture memory and a polygon budget, limited modeling ability, limited animation ability etc etc, I don't think artists are too upset about some video artifacts when everything else had to be compromised.




will this work? (provided you feed +5v / GND on the appropriate pins)
Not properly. You need to put 75 ohm resistors on the output pins and 100 nF (0.1 uF) or larger ceramic capacitors on the inputs. You should also put the same kind capacitor between "Vs+" / 5V and GND.

I also can't say whether or not the sync signal will work, it's only a hunch that it's digital, it would take quite a bit of work to find out for sure. If it's really an analog signal then you can use a 4 channel amplifier and wire it the same as the RGB lines.


Also what is "output enable input" pin on the 74AHCT1G126GW (datasheet link (http://www.datasheetcatalog.org/datasheet/philips/74AHCT1G126GW.pdf)) , do we need it?
It needs to be connected to VCC / 5 V.

[keropi]

[...]

Not properly. You need to put 75 ohm resistors on the output pins and probably 0.1 uF/100 nF or 220 nF (or larger if you have them) ceramic capacitors on the inputs. You should also put the same kind of ceramic capacitor between "Vs+" and GND.

I also can't say whether or not the sync signal will work, it's only a hunch that it's digital, it would take quite a bit of work to find out for sure. If it's really an analog signal then you can use a 4 channel amplifier and wire it the same as the RGB lines.

It needs to be connected to VCC / 5 V.

right, thanks for the extra components list :)
isn't evidence that the sync signal is analog since we already pass it through the amp that gtsamour mentions and it works?
Also can you recommend a 4-channel amp suitable for it ? (I am more of a "monkey see - monkey do" person, I can build stuff if someone tells me how...)

[Calpis]

isn't evidence that the sync signal is analog since we already pass it through the amp that gtsamour mentions and it works?
Digital signals can pass through the amplifier as well, but they may be distorted if they are too large. One reason I believe it's digital (besides sync usually being digital) is because of that circuit, notice how they changed the 10 ohm resistor to 300 ohm on sync (which is dumb because it's not a common value), if it were a TV ready signal it could use the same amplifier.


Also can you recommend a 4-channel amp suitable for it ?
The THS7374 looks really really good:

http://www.ti.com/product/ths7374

It even allows you to bypass the reconstruction filter I was talking about in the last post, and it has a bandwidth exceeding the frequency components of the PCE's DAC, so you'll get maximally sharp pixels on your display if it's constructed well. Even if you don't use the 4th channel because sync is digital it's still a good buy, they don't have a similar chip in 3 channels.

[keropi]

^ nice , and it looks they are 4-5$ on eBay... is it correct to assume that if I want I can just connect the composite output of the EXP port and not have to worry whether c-sync is digital or not?
from TI's site I gather I feed it the 4 signals , put a 100nF cap between GND/Vs+ and on the output 75ohm resistors... Do I still need 100nF caps in the input signals?
Also will the 7374 be sufficient for the N64 too?

[APE]

The 7374 is superior to what I've been using in N64s from the looks of things. Not sure if it would produce a noticeably improved picture but it is sure worth trying out.

Damn shame Digi-Key doesn't stock the part.

This might prove more useful for the N64:
http://www.digikey.com/product-detail/en/THS7316DR/296-26684-2-ND/1905373

36mhz.

Though it requires 5.5v. Most people seem to want to run the THS7314 off 5v when it wants 3.3v. The datasheet says 5.5v is the maximum but that extra voltage has to go somewhere.

[Calpis]

is it correct to assume that if I want I can just connect the composite output of the EXP port and not have to worry whether c-sync is digital or not?
Yes if you only intend to connect it via SCART. Most likely the composite signal won't be able to drive a TV directly, but you can use the 4th amplifier.


from TI's site I gather I feed it the 4 signals , put a 100nF cap between GND/Vs+ and on the output 75ohm resistors... Do I still need 100nF caps in the input signals?
You can try without the input caps and see if it works. If it works definitely omit them. The reason I suggested it is because the bad circuit suggests that the DAC is biased towards V+ instead of GND, and if the level is too high the amplifier will clip while trying to amplify it. Using the capacitor is a sure way to remove the DC bias and it will have minimal effect on the video quality.


Also will the 7374 be sufficient for the N64 too?
Absolutely, the bandwidth may not encompass all the DAC's frequency components like PCE, but "just" 60 MHz would be have excellent pixel edges much less 150 MHz.


Not sure if it would produce a noticeably improved picture but it is sure worth trying out.
Are you using the THS7314? If so on a TV maybe not, the '7314 is limited 8.5 MHz by its filter, which is probably the upper end of TV bandwidth. Newer broadcast monitors and arcade monitors could definitely benefit from the '7374.


36mhz.
36 MHz would be acceptable for N64, it passes the 5th harmonic allowing pixel edges this steep:

http://www.paladinmicro.com/images/ForumPosts/SqWav5thHar-01.png

Over 60 MHz would capture the 9th harmonic which is this steep:

http://www.paladinmicro.com/images/ForumPosts/SqWav9thHar-01.png

The '7374 will have an extremely steep slope.


Though it requires 5.5v.
?? It doesn't REQUIRE 5.5V, it tolerates up to 5.5V but it will run off as low as 3V.


Most people seem to want to run the THS7314 off 5v when it wants 3.3v.
?? It doesn't want 3.3V.


The datasheet says 5.5v is the maximum but that extra voltage has to go somewhere.
?? It's not a voltage regulator, there's no consequence for using 5.5V over 3V, in many cases 5.5V will be NECESSARY. You WANT a wide rail to rail potential so your signal doesn't end up clipping. RGB signals are 0.7 V, composite is 1.1 V NEGLECTING any biasing. These amplifiers have a gain of 2, so the outputs must be able to swing 1.4 V and 2.2V respectively. At 3V there is very little headroom to account for any DC bias, plus the output signal cannot actually reach either rail, these modern IC amplifiers are able to get pretty close though, like 0.2 V or so. So at 3V amplifying composite you'd have no choice but to remove any DC offset. Typical bipolar outputs can clip at 0.7V even higher from either rail...

[APE]

Keep in mind Caplis I'm still learning (logic design starts August 11!). The datasheet for for the 7314 claims to want 3.3v with a maximum of 5.5v. I've wired the 7314 for 5v and 3.3v without any noticeable difference on my Sony PVM displays.

Probably will try a 7374 in another however I'm not sure I'll be capable of seeing a difference on something almost 20 years old.

Or this:
http://www.digikey.com/product-detail/en/THS7353PW/296-19328-5-ND/948538

150mhz.

[Lum]

"Wrong shouldn't have air quotes,"

It would have been incorrect to not place a qualifier around the word wrong. If I didn't it would've made my statement too open to misinterpretation. I had to avoid sounding like I was trying to debate dictionary definition of wrong.

"it literally is wrong"

I never said it otherwise.

"and yes it does mean intolerable and mediocre at least."

Context. Video quality that a user experiences is not necessarily intolerable and mediocre with wrong circuits. Instances of working or non-working are known to occur.

[keropi]

Yes if you only intend to connect it via SCART. Most likely the composite signal won't be able to drive a TV directly, but you can use the 4th amplifier.


You can try without the input caps and see if it works. If it works definitely omit them. The reason I suggested it is because the bad circuit suggests that the DAC is biased towards V+ instead of GND, and if the level is too high the amplifier will clip while trying to amplify it. Using the capacitor is a sure way to remove the DC bias and it will have minimal effect on the video quality.
[...]


does this look like something that will work, or will it burn up when powered? (using or not the caps in C/R/G/B input depending if it works...) :excitement::excitement::excitement::excitement:

http://i47.tinypic.com/msexdi.jpg

[Calpis]

Keep in mind Caplis I'm still learning
Few people ever "finish" learning electronics. I'm 9 years in and I'm not halfway to where I want to be.



on something almost 20 years old.

I've been checking CRT bandwidth figures:

-ancient PVM: 10 MHz
-late Wells Gardner 15 kHz: 15 MHz
-late Wells Gardner 15/24 kHz: 22 MHz
-late PVM (20L5): 24 MHz
-late BVM (20F1U): 30 MHz
-current Wei-ya 38" (!!!) tri-scan: 65 MHz
-late Wells Gardner tri-scan: 70 MHz
-current Wei-ya VGA: 135 MHz

Some consumer PC monitors are claiming up to 350 MHz... Not sure how valid that is since video signals must be amplified 50-150x to drive a CRT.

Arcade monitors seem like the best compromise for purists. Not only do they have the best value, they're super elegant with their fully analog signal paths. Any HD video you'll be wanting to view on a fixed pixel/digital display anyway so they have the potential to be pretty much the end-all CRT. The only things pricy broadcast monitors have on them is color accuracy and geometry, but unless you get a self-calibrating one I think even that goes with time.


Video quality that a user experiences is not necessarily intolerable and mediocre with wrong circuits. Right, but usually that's all thanks to the TV.


does this look like something that will work, or will it burn up when powered?
I think it'll work. You should get this http://www.ebay.com/itm/320900381229 and solder everything to the through-holes

[keropi]

[...]
I think it'll work. You should get this http://www.ebay.com/itm/320900381229 and solder everything to the through-holes

thanks again for the help, I'll order the parts and let you know when they arrive , I am most eager to try this on the n64 first, I don't think the current amp installed is a good one , it's just some transistors (got it pre-modded)

[Lum]

You asked for it so here's a big reply:

"blatant significantly inferior"? It doesn't, look at the comparison video posted earlier. Most people have no objection to composite's sharpness, they object to the video artifacts (which actually is a kind of modulation distortion), and the artifacts can be improved by using a better comb filter, or removed entirely by using S-video.

Sharpness is dependent on bandwidth, the more high frequency content is allowed to pass, the sharper pixels may transition. RGB obviously has the most bandwidth, but S-video was designed to give you the same viewing experience at a significant reduction in chroma bandwidth, and it succeeds with more or less color bleeding. Composite is S-video transmitted on a single wire instead of two; to achieve this luma (which is responsible for the majority of sharpness we see) must also go through a significant reduction in bandwidth so both can fit into the frequency spectrum of a broadcast TV channel (only 6 MHz for NTSC). That said, I don't think the luma bandwidth allotted for composite is insufficient for viewing most PCE(/FC/MKIII/SFC) video... I don't think it's even insufficient for viewing MD (/lowres PS/SAT/N64), you can still make out pixel boundaries with a clean signal.

Right. The video artifacts never should've reached such prevalence. TV makers by that time had begun placing RGB inputs internationally. The right push may have convinced them it'd help standardize components used between regions, and hope word of mouth about RGB gaming's beauty would drive TV sales.

Cheaper console manufacturing and reduced design complexity is a benefit of RGB-only also. Less need to worry about encoders, color systems, or filtering. (apologies if this was mentioned before)

In the end it's somewhat redundant to apply a composite filter on RGB capable consoles. That's just trying to restore quality previously degraded. Cause and effect, start from s-video or RGB so you don't have composite artifacts as part of the signal chain to begin with.

[keropi]

after all this time finally everything arrived... the TSSOP14 to DIP14 adapters and the amps themselves:

http://i50.tinypic.com/bfqubt.jpg

now I only need to solder the amps on the adapters, they are pretty small :livid: , any advice before I try it? or do I just flux the pads and heat with the iron with the IC in place (I think that's what I have to do) ?

[Bad_Ad84]

If you struggle, I can solder them all on for you and ship them back.

Dont want anything for it :)

[keropi]

If you struggle, I can solder them all on for you and ship them back.

Dont want anything for it :)

awesome, thanks for the offer Bad_Ad84 , I'll try to solder them my self first and if I fail I will take up your kind gesture :)

[keropi]

well, unless the THS IC is super sensitive to heat I think I managed OK for a first time smd component soldering :sneakiness:

http://i45.tinypic.com/15wasd5.jpg

will try the amps tomorrow and let you know how it goes

[keropi]

OK finally today I managed to do some testing:

http://i125.photobucket.com/albums/p55/restqp/IMG00688-20120820-1536.jpg

it's a half-assed test mind you because the 100 and 200nf caps have not arrived yet. I used some 68nf caps for the test , so they are the wrong value. I also did not put a cap between gnd/vcc because I did not have another 68nf one.
I also did not connect to the GND the BYPASS+DISABLE+NC+NC pins, they are all just NC. I did not get a picture with them all connected to GND and I thought this was to blame LOL. But I found out later that without the caps there was no picture at all. With the 68nf ones I get this result:

http://i125.photobucket.com/albums/p55/restqp/th_IMG00684-20120820-1535.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00684-20120820-1535.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00685-20120820-1536.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00685-20120820-1536.jpg)

http://i125.photobucket.com/albums/p55/restqp/th_IMG00686-20120820-1536.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00686-20120820-1536.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00687-20120820-1536.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00687-20120820-1536.jpg)

I suppose when I try the 100 or 200nf the picture will improve...


edit: found another 68nf cap, put it in gnd/vcc but made no difference as expected... got some more shots though, I have moving pixels in the upper left , upper right and lower right corners of the logo box, where you can see the gfx errors.

http://i125.photobucket.com/albums/p55/restqp/th_IMG00689-20120820-1550.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00689-20120820-1550.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00692-20120820-1551.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00692-20120820-1551.jpg)

http://i125.photobucket.com/albums/p55/restqp/th_IMG00691-20120820-1551.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00691-20120820-1551.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00690-20120820-1550.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00690-20120820-1550.jpg)

[Chilly Willy]

Remember that the PCE signal is nowhere near "broadcast compliant". I have a VCR and two LCD TVs that absolutely refuse to accept the signal my SGX generates, and another LCD monitor with video in that shows "flagging" for the first dozen lines of the display. So your glitches may have nothing to do with your circuit and everything to do with the timing your TV expects from the signal.

[keropi]

the monitor I tested with worked fine with the old rgb-amp that was discussed before , so I keep my hopes up that it will work with the 7374 too :)
I got some 100nf caps today, will try them later and report back!

[keropi]

100nf caps made a huge improvement (this time there is a cap between gnd/vcc and all unused pins are grounded) , there is still some discoloration effect mainly in the top and bottom parts of the screen though , and judging from the title screen there is also some kind of ghosting(?) when the color difference is great as it shows in the bottom corner of the logo box.

http://i125.photobucket.com/albums/p55/restqp/th_IMG00693-20120821-1123.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00693-20120821-1123.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00694-20120821-1123.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00694-20120821-1123.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00695-20120821-1123.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00695-20120821-1123.jpg)

http://i125.photobucket.com/albums/p55/restqp/th_IMG00699-20120821-1124.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00699-20120821-1124.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00700-20120821-1124.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00700-20120821-1124.jpg) http://i125.photobucket.com/albums/p55/restqp/th_IMG00701-20120821-1125.jpg (http://s125.photobucket.com/albums/p55/restqp/?action=view&current=IMG00701-20120821-1125.jpg)

still waiting for the 220nf ceramic caps, but I can't help but wonder if 220nf is way too much...? maybe I need to search for some middle value (if it exists) ?

edit: also tried on a CRT tv, I get the same effect... when there is an object with great color difference it creates a horizontal "shadow" across the screen... for example the 1st moving platform in wonderboy creates a shadow that moves across the screen with the platform, seems like there is a luminance drop or something... also notice the grass on the ground, it has pink in it...

[Calpis]

The datasheet recommends 100 nF, and also specifies the input impedance to be 800k ohm. Together they make a high-pass filter corner frequency of 2 Hz... This is PLENTY low enough. You can use higher capacitors, but it won't make any difference.

You REALLY should follow the recommendations of: putting a 100 nF decoupling capacitor across GND and 5V, also a larger electrolytic, like 22 uF across them as well to minimize power supply ripple (not as necessary). They also specifically say to not leave the control signals floating! GND DISABLE and BYPASS.

[keropi]

Thanks for the input Calpis but keep in mind that on the 2nd attempt I do have 100nf ceramic caps in all inputs, all extra pins are grounded together and there is a 100nf cap between GND+VCC , just like the rough drawing I did before:

http://i47.tinypic.com/msexdi.jpg

it seems to me that it needs some slight tweaking to get it perfect on the PCE... but I have no idea what to try next

[Calpis]

I don't think you should GND NC. Also your 100 nF decoupling is probably not effective (can't see how you wired it), you should solder the capacitor directly to pin 9 (GNDed) and pin 10.

The only way to know for sure what to do next is to use an oscilloscope on the signals... That way the levels could be verified in and out of the amplifier. I think they are fine though.. The interference is low frequency like a GND loop. Does the interference stay static or does it move around? Try larger capacitors at the input and see if that clears it up. If it doesn't I suggest decoupling 5V with the 22 uF cap.

[keropi]

Thanks for the suggestions Calpis, I will make the corrections suggested and take a recent pic tomorrow so you can see.
Also how do I decouple 5v with the cap? Can you tell me what points to connect?

I made a pic from an emu shot so you can see what kind of distortion I have (other than the bottom + lower parts that are apparent in the pics and are static)

http://i46.tinypic.com/2d81iyh.jpg

Now the platform on the right moves up and down. If you see I have darkened horizontally the screen across - left and right of the platform -, as thick as the platform itself. Now imagine that darkened area moving with the platform up and down. Is this because of a ground loop? Sadly I don't have an oscilloscope or easy access to one...
So to recap: upper+bottom parts have this static distortion and moving parts on the screen that have big color differences (like the platform vs. solid background) have moving shadow at the screen.

Maybe you can guess a workaround based on the fact that the previous rgb amp that was discussed here worked with great quality? Maybe calculate how much it reduces/enhances the input? I don't really know since I lack the needed knowledge , maybe this suggestion is crap, just thinking...

[keropi]

@APE : this cap is connected where? on the 7374 amp? because I already have a 100nf cap connected between vcc+gnd on it...

[keropi]

ok here is a quick pic of how I connect the thing:

http://i45.tinypic.com/2n8r1pv.jpg

I have left the 2 NC pins floating, and GND+BYPASS+DISABLE are all connected to GND.

I have tried with 100nf caps for input and decoupling: you can see the mediocre results in the previous posts
I have tried with 150nf caps for input and a 100nf for decoupling: somewhat better results but I had some flashings and shadows
I have tried with 220nf caps for input and a 22mf for decoupling: the best results so far, there is little discoloration in the up+bottom parts of the screen and there is no moving shadows from the platform for example... BUT the colors look a little washed up and there is some faint shadow ripples in the background, gnd problem?

In all situations the pixels are VERY sharp and clear, even if they have the wrong colors but the overall result is nowhere near the old rgb amp, it might have less sharp pixels but the colors are more vibrant and there is no discoloration or shadow effects at all...
IMHO (and my limited knowledge on the matter) it must be a matter of finding the correct values that PCE outputs and adjust the input to the 7374 amp.

I am open to suggestions and corrections , I don't want to give up the 7374 yet for the PCE :)

edit: if you notice I am not using composite on pin1 but sync , just like the old amp... I just realized this since I did this some time ago to avoid the background lines effect on lcd...

[Calpis]

The 5V decoupling should be 22-100 uF according to the datasheet, not mF. Each capacitor size + construction corresponds to a different useful frequency range, when it's too far out of range it's not effective at decoupling.

I didn't mean 100 nF OR 22 uF, I meant BOTH. The 22 uF isn't very important, it can be soldered to the adapter, but the 100 nF should be soldered directly to the chip and the leads should be shortened to 1 cm or so.

One thing that the old amplifier has is AC coupling on the output. This might be important to your TV depending on how it's designed. You can add this to the THS amp by putting 220 uF C in series with the RGB outputs (+ towards the amp), then putting the 75 R after. Other than that I don't see what can be "wrong", the old amplifier doesn't really do anything, so all I can think of is that the PCE's signals swing too wide and distort with the THS which tries to amplify them 2x. The way to fix this would be to measure the signal going into the amp, then attenuating it with resistors.

[keropi]

thanks for the info (again) I will make corrections/additions tomorrow and see what the result is :)
I have tried with both an LG lcd and a CRT tv, they both display the same flaws in the image... I hope I get better results tomorrow, the 7374 really produces a sharper image which I like :)
the amp looks quite horrible atm with all that experimentation, I just was bored making it look nice and having to replace the caps later... I hope it does not get burned or something LOL...

thanks again Calpis!

[Hedgeyourbets]

There's something about the threads on this site which never cease to make me feel stupid haha
I get sick of people spouting the "it wortks therefore it's fine" crap when it comes to other things "oh yes my hard disc makes a dreadful clicking noise and everytime my computer boots up it warns me that the drive is throwing out SMART errors like nobody's business but ya know, windows boots up so clearly everything is fine and dandy.
Yet I've been trotting along with the same naievety when it comes to console modifications :/ I wish I understood properly, ignorance isn't bliss, it's sad and boring :(

[keropi]

OK, today I built this little monstrosity :biggrin-new: according to the info given, it's ugly but remember it was for testing...

http://i47.tinypic.com/2q1c2oo.jpg

it works but with a mediocre result... I don't like it and there is still discoloration in the upper+bottom parts of the screen... it's less but it's there.
I am abandoning this project for now because obviously signal measurements are needed and I cannot provide them... :(

I will now try and install this in my N64 and replace the existing amp , should be way simpler according to mmmonkey's guides...

[keropi]

well, at least the N64 amp replacement was a smashing success, I get a less blurry picture now:

http://i48.tinypic.com/aaxglv.jpg

http://i46.tinypic.com/2ls6xyd.jpg

http://i49.tinypic.com/29vze35.jpg


also we were discussing the PCE-7374 troubles with gtsamour and he found this schematic that uses different amps but works fine:

http://i48.tinypic.com/k0k1te.jpg

and this drawing:

http://i45.tinypic.com/r8dt9x.jpg

do they give any kind of clue? maybe use electrolytic caps for input/output?

[wilykat]

Usually a + by capacitor symbol indicates electrolyte caps. Most capacitors are non polarized (can be used either direction) while electrolytes are polarized.

[Calpis]

The NJM amp does the same thing as the THS, except worse (well, it has sag correction which is nice).

10 uF on the input won't help here, the THS amps have very high input impedance which means they don't need very large input capacitors to get good low-frequency response.

I looked in the THS datasheet, it seems for AC coupled signals you need an external pullup resistor.... That's probably what the issue is. They say to use ~5.36 M resistors for 5 V midpoint biasing, not the easiest value to get... Anyways keep the 100 nF caps. Also since there will be a DC bias on the output, you should really keep the 220 uF output capacitors.

[Segata Sanshiro]

Very interesting read this thread. I recently made something similar to the mmmonkey guide. I did however switch the c-sync for composite video as I couldn't get an image at all on certain TVs in my house, although for the two screens it did work for there's not much difference.

Would definitely be interested in using a more effective solution, which would you recommend Calpis? You seem to know your shit. :D

[Calpis]

I'd go with the THS, it won't be easy to find a better amp for the price, and with the PCE it's 3x better than necessary for a good picture. Discrete amps and older IC amps can't hold a candle to it really.

[keropi]

Just an update, I got a refund from the eBay HK seller I got the 7374 chips from, no questions asked... I just had to send him a pic of them destroyed.
He might be a good seller or not caring for 20$ or simply knows that they might be dodgy parts and not bother more with them...
Since then I got some 7314 from Bad_Ad84 and will give them a shot...

[Segata Sanshiro]

Another question, is composite video or composite sync best for sync?

[Bad_Ad84]

I got some of these amps from a legit seller, rather than a dodgy chinese seller. Will test them out at some point and see if I get better results than keropi

[keropi]

Another question, is composite video or composite sync best for sync?

Using c-sync can help in LCD tv sets, you avoid some jailbar effect... on crt sets it doesn't make a difference AFAIK

@Bad_Ad84 : yeah it will be interesting to see your results, the 7374 seems a VERY good chip , I hope you succeed!

[Segata Sanshiro]

Bad_Ad84, let me know how it goes. If you'd like a PC Engine to test it with then let me know too, perhaps. ;)

I've had more success with composite video honestly, but it seems to have more motion blur.

Also on my Ferguson CRT the image switches to 16:9 as per RGB specification (5v being 16:9 on the 8th pin) - how would I bump this so that it sets to 4:3? :)

[Bad_Ad84]

Let me finish up the stuff I have piled up here already, then we can sort something out.

[TPSNT]

Also on my Ferguson CRT the image switches to 16:9 as per RGB specification (5v being 16:9 on the 8v line) - how would I bump this so that it sets to 4:3? :)
I had exactly the same problem with my Mega Drive RGB cable. Because the Mega Drive only provides 5v I have used a SIM1-0512 to get 12v on SCART pin 8.

http://i.imgur.com/48Kwi.jpg

[Segata Sanshiro]

Awesome, thanks for the post!

[Bad_Ad84]

Thats good for consoles that natively output RGB.

But if you are making your own RGB mod and cables for it, might as well put 8-12v down one of the wires.

or just disconnect it completely and manually change channel. It will default to 4:3

[Segata Sanshiro]

So that would involve removing the 8th pin from the SCART connector? If so I'd probably just do that then. Haven't tried that.

[Bad_Ad84]

Yes, just desolder the wire in the scart end, so you can reattach it if you ever need to.

Should work just fine then, but you will need to manually switch channel.

[Segata Sanshiro]

Hmm, my TV has no "RGB" mode and removing the 8th pin just results in no image.

[Bad_Ad84]

Weird, every TV I've had just works if you put it on AV1 (or 2, which ever it is). Pin 16 is RGB/Composite switching pin.

Options are the DC/DC converter then.

You can send me the lead with the PCE when we get around to it if you want.

[veganx]

I've found the 7374 here in Brazil. At least I think this is the one:

http://produto.mercadolivre.com.br/MLB-434103571-ci-circuito-integrado-tda-7374-_JM

http://produto.mercadolivre.com.br/MLB-435396211-tda7374-circuito-integrado-tda7374-promoco-_JM

What do you think? This seems legit?

[Segata Sanshiro]

http://i45.tinypic.com/r8dt9x.jpg

How would I change this for use on the PCE, or is it suitable in the same way that it is on the N64 as per the mmmonkey guide (http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb_new.htm)?

[Calpis]

-10 uF is too big for this amp, you only need 100 nF, and ceramic caps don't have polarity issues and are more reliable.
-The inputs *need* pull-up resistors to bias the amp, and if you do use polarized capacitors, + should be at the higher potential which is usually towards the amp. The only time you don't need the pull-up resistor is when you have a DC coupled signal (such as with N64), but with DC coupled signals you don't want to AC couple them with an input capacitor.
-You want the 100 nF cap decoupling the 5 V rail, it should be as close to the power in as possible.
-It's better to put the series output capacitor before the resistor.