Saturn SCART quality issues

[Druid II]

After seeing the terrible quality of the play-asia RGB cables, I decided to do a direct SCART output onto my Saturn, removing that 10-pin bastard connector and soldering the output directly to the motherboard. Currently, I have a small ribbon cable inside the machine, that carries video output from the Saturn motherboard into an internal USB connector I removed from a spare PC motherboard - it was the only small enough connector I could find with enough pins. (soldering directly to the motherboard would be a permanent solution, which I why I did this)

This shebang is connected to the SCART output, wired up according to this diagram:



... except for pin 8 (aspect ratio control) which I omitted, and the audio/composite input/output pins switched around, as I attached a female connector while the diagram is for a male one. (just exchange pins 2, 6, 20 with 1, 3, 19). Ground pin is daisy chained.

Now, the problem is, I have this wobbly washout ontop on the picture, most visible on yellow background (ex. Virtua Fighter Kids title screen). It's the exact same problem I had with the play-asia rgb cable. I figure this happens because the scart connector takes h/v sync info from the composite video signal, and the extra video data causes interference. Now, the Saturn outputs composite sync on a separate cable, and sure enough, using that in place of composite video removes the washout entirely.

However, if I use pure sync, the picture is jumping up and down! Like, randomly once or twice every second. How should I go about fixing this? What could be the cause? The cables I use are all well shielded and high quality, so that can't be the problem...

For the time being, I've connected both c-sync and composite video to the same pin, this reduced the washout effect significantly, but it's still annoying enough.

Moreover, if I switch from 50hz to 60hz, the washout effect is removed. (I've yet to try c-sync only with 60hz output). This is only a partial fix because I have quite a few PAL games which are optimized for 50hz, so I'd like to have 50hz too.

[Jamtex]

Because the Saturn doesn't give the correct voltage on pin 8 (technically for 4:3 RGB it should be between 9.5V and 12V with just under 3V on pin 16, although the official pertitel standard has large gaps between the voltages and 2 to 5V is basically undefined...), the TV gets confused and tends to switch between normal and widescreen modes (hence the flickering when you do use composite sync), however most TVs do allow you to select between widescreen (16:9) and non widescreen (4:3) modes (overriding what the SCART input is asking), so press the ratio or widescreen button a few times and it should clear it. Some TVs will allow you to select default aspect ratio in setup, for example the Panasonic CRTs in allows you to select Auto, 4:3 or 16:9 for ratio, so by forcing it to be 4:3 it should stop flickering.

Most TVs do tend to strip the composite sync from the composite video although I did notice that some if they are not getting the correct voltage on pin 8 (and/or 16) will see the composite video signal and assume it is composite video and the RGB lines are interfering with the composite signal.

It's not just the Saturn, the official Sony SCART lead on a Sony TV on the Playstation 1,2 or 3 will always select 16:9 mode...

[Codeman]

The schematic show pins 8 and 16 bridged with a resistor.

I had and official RGB cable that didnt seem to output RGB, the TV just didnt swith into RGB mode, I found out the cable wasnt outputting enough juice on one of these pins. I ended up bridging these pins with an isolated paperclip and in seconds I got my crystal clear RGB picture.

Maybe your problem is also related to one of these pins, check if enough power is being outputted to these pins

[karsten]

weird you have such problems my saturns output perfetc and cristal clear rgb through my scart connectors...

are you sure you haven't got a composite cable with a scart end instead of an rgb scart?

[Segata Sanshiro]

It's not just the Saturn, the official Sony SCART lead on a Sony TV on the Playstation 1,2 or 3 will always select 16:9 mode...

The PS1 version perhaps, my PS2 official cable does everything perfectly.

[Druid II]

Okay, I took some measurements. C-Sync signal was 1.74v, which I guess is out of spec because adding a spare 300ohm resistor made the picture stable (with the resistor in, c-sync signal dropped to 0.51v)... except that now hi-res mosaics show rainbowing. I combined composite and c-sync into one line and put the 300ohm resistor onto that, and now the picture is pretty damn good in both pal and ntsc modes. Now I'll just have to deal with the noisy audio. Not sure how could I add RCA out and keeping the internal connectors - I doubt another cable would fit into that end...

Out of interest, what is the voltage spec for c-sync in scart? 0.75v? How much resistance would I need to have that exact voltage?

[Jamtex]

Composite sync has a peak to peak voltage of between 0.5 to 2V, although 1V is normal.

Did you try just using C-Sync and forcing your TV to be 4:3?

[Oldgamingfart]

I read somewhere that the Japanese Saturn has the extra voltage on C-Sync, so normal PAL RGB SCART cables won't usually work properly without modification.

With the Gamecube SCART, there's usually x3 capacitors on the RGB lines, maybe the same can work for the C-Sync (220uf capacitor: + side to C-Sync wire, - side to SCART pin 20).

FYI the PAL Saturn RGB SCART cable I have here (I think it's official), doesn't have a resistor on the +5 line (direct connection), and pin 5 is not grounded either. Pin 4 and 18 are grounded, but not to the outer metal shield on the SCART end.

*EDIT*

Right, found a 220uf cap and soldered it onto the composite line as explained above. I'm using a Panasonic video monitor to test with, so here's a picture of the naked SCART plugged into the SCART extender. You can see the 220uf cap soldered on:



Let's power it up:



Ooh very nice! Image might appear a little stretched, as I have the monitor's geometry controls set for PAL SNES use. Prior to modification, plugging in the SCART cable used to make the picture jump around like a badly tuned analogue TV station.

[Druid II]

FYI the PAL Saturn RGB SCART cable I have here (I think it's official), doesn't have a resistor on the +5 line (direct connection), and pin 5 is not grounded either.

The resistor on the dc line is there, I guess, so it can supply the 3.whatever volts which trigger RGB mode instead of a notably higher value. Some TVs may not like it if a much higher voltage is supplied instead of whatever it is that triggers RGB mode.

I read somewhere that the Japanese Saturn has the extra voltage on C-Sync, so normal PAL RGB SCART cables won't usually work properly without modification.

PAL (and maybe usa?) Saturns have 9v dc in place of c-sync on the a/v connector. It still has c-sync internally, it's just not connected to the a/v connector.

This makes no difference cause I soldered the cables straight to the motherboard.

It also doesn't make any difference anymore cause the machine died. Literally when I was finally finished with everything, and took some last measurements to check if the order of the region switches is correct. That's 2-3 weeks of work nixed out in the last fucking minute. Nice way to finish the year.

[Oldgamingfart]

Oh dear, sorry to hear that. A small clarification, when I said C-Sync, I meant Composite Video (Pin 20). Yes it appears that my cable has Pin1 (9v in place of C-Sync), going direct to pin 16 of the SCART (no resistor) - Pin 8 (aspect ratio) on the SCART side is not wired at all.

Not a problem when using a monitor, but this would mean no RGB switching voltage (when using an official PAL RGB SCART cable with a Japanese Saturn)! I suppose you would need to strip back the Saturn connector and re-wire pin1 to pin4, or use a resistor and 9v battery.

[Druid II]

Yeah, there's a thread at nfggames about removing the TP4 connector (c-sync) and linking it into 5v to get the rgb cable working on a japanese saturn.

[swcdx]

Hmmm....

I was just about to put together a Saturn setup using a stock, US Saturn, an XRGB3, and a stock SCART RGB cable ... but you are saying the SCART RGB cables for the saturn produce poor quality ?

Were there any SCART RGB cables produced for the saturn that output high quality RGB ? I'd love to be able to put this setup together without any custom work ...

Thanks.

[Druid II]

The poor quality was caused by the cheap crap playasia cable, which was unshielded and low quality. I soldered a scart output onto the console motherboard and connected that with a high quality scart cable, and the video quality was very good. Even if it took some tinkering to get it right. Audio was still a little noisy, though.

[swcdx]

ok, but were there ever any "good" saturn->scart cables produced that I could purchase, as opposed to the "bad" playasia one ?

I plan on doing RGB output, via SCART, from a saturn, but I am not going to be doing any surgery for it ...

[Druid II]

I heard Adaptorman (ebay) and consolegoods.co.uk sells good cables.

[mooseblaster]

As far as I was aware, all PAL Sega Saturns came with official Sega RGB SCART cables.

[LeGIt]

As far as I was aware, all PAL Sega Saturns came with official Sega RGB SCART cables.

No console as far as I can remember has ever shipped with a fully wired RGB SCART cable out of the box, especially not the Sega Saturn!

Most things shipped with a RF unit until the last few years where they were shipped with a crappy composite/RCA + SCART adapter instead.

[Shakey_Jake33]

As far as I was aware, all PAL Sega Saturns came with official Sega RGB SCART cables.

Actually, Sega switched back to including a RF cable sometime in 1997 (or maybe even before?). I remember I made a point of buying a new TV with a Scart socket specifically so I could then buy a Saturn, only to find my Saturn came with an RF cable anyway.

The fact that the official Sega Scart cable is not fully wired is actually a useful way to know if your cable is official. That said, I use this cable on a Japanese White Saturn without needing to modify the cable.

[mooseblaster]

No console as far as I can remember has ever shipped with a fully wired RGB SCART cable out of the box, especially not the Sega Saturn!

Note: a SCART cable does not have to be fully wired to be RGB. In fact, having a fully wired cable is commonly detrimental to its performance as cross-talk from the input wires causes picture and sound bleed-through - which is why I ended up clipping the input wires from my SCART switchbox after I constantly heard faint audio from BBC1 when things were quiet in a game!

[LeGIt]

Meh are you sure it wasn't because of a tinfoil hat? ;)