CRT image issue - I'm really starting to lose my patience

[Prometheus]

Basically, I had to move a few months ago and wasn't able to bring my behemoth CRT that I was previously using. I've been trying to find a good replacement CRT that's not too big, and has great image quality. I've bought numerous TVs and they all have the same issue. I'm sick of wasting money on the damn things, so maybe someone more knowledgeable than I am with CRTs could help me find a solution.

I believe the term for my problem is called "speed bumps", where an image moving across the screen kind of goes in and out like a wave. It almost seems like the screen compresses in the middle, and when the image moves, it expands on the left and right sides. This makes playing 2d games like Mario or Sonic almost unplayable, or at the very least, it adds a distraction that shouldn't be there. And considering I'm using the CRT mainly to play retro 2d games, that's really a problem.

I've tried using the service menu to fix the issue, but so far no luck. Of course, it doesn't help when 85% of the menu is a bunch of abbreviations I don't understand, so maybe the setting is there and I've yet to find it.

Does anyone have any advice? Is this even fixable, or should I just give up?

[APE]

I think I know what you're talking about and you aren't nuts at the very least. Assuming my assumption is correct, its due to the tube being curved either outwards or inwards. My parents bought a "flat" CRT years ago that had this problem in spades and you could really see it with the scrolling bar at the bottom of news stations. With standard tubes it tended to be the opposite.

My Sony Trinitron doesn't seem to have the problem nearly as bad as some displays I've seen but it is a "flat" tube from what I understand. Probably should look into it.

What display are you currently using?

[Prometheus]

Sorry, I should have mentioned that in my first post. The one I'm currently using is a 27' flat screen Sony Trinitron WEGA KV-27FS120.

Is this a flat tube issue? I always assumed flat screens were introduced to avoid this type of problem.

[XxHennersXx]

can you take a picture to show what you mean? I think I have an idea of it but I want to be sure.

[APE]

The Trinitron I have is a very similiar model albeit 32" instead of 27". Honestly I'm not sure what flat tubes were supposed to do beyond a selling point but Wikipedia claims:

Flat CRTs reduce the amount of glare on the screen by reflecting much less ambient light than spherical or vertically flat CRTs. Flat screens also increase total image viewing angle and reduce overall geometric distortion.

[Yakumo]

I know the problem you are talking about but I've never seen it on any of my CRT screens over the years. Either the TV you are using has a cheap tube in it or it's just a poor model. Over the years I've have many CRT screens. My first was a NTT Nokia that had a slightly curved screen, then after that a Toshiba curved screen, Toshiba flat screen, Sharp curved screen, Mitsubishi flat screen and finally a JVC (Victor) flat screen. Not one of them had the "speed bump" issue. This is the price you pay when buying cheaper tubes.

Yakumo

[Prometheus]

Unfortunately, I can't provide any pictures. All I have is an atrocious, cheap cell phone camera that barely works.

Even if I could get a decent picture, it wouldn't be very noticeable since the issue mainly occurs when the game is in motion. I'd need to record it to show what I'm talking about and I have no way of doing that.

The Trinitron I have is a very similiar model albeit 32" instead of 27". Honestly I'm not sure what flat tubes were supposed to do beyond a selling point but Wikipedia claims:

Flat CRTs reduce the amount of glare on the screen by reflecting much less ambient light than spherical or vertically flat CRTs. Flat screens also increase total image viewing angle and reduce overall geometric distortion.

Bullshit, at least from my experience. Every flat CRT I've purchased had horrible geometry problems that had to be corrected in the service menu. Even then, there would always be one side that was crooked or curved. The only issue I could never really fix... is this one.

EDIT: It wouldn't surprise me if the TVs I've bought were cheap models. The previous TVs I bought were done with little to no research, since I bought them at thrift stores whenever I found them at a decent price. However, I intentionally looked for a Sony Trinitron WEGA since I heard they are supposedly great TVs with little to no problems.

Am I just having REALLY bad luck?

[XxHennersXx]

I've had no issues with flat CRTs...I <3 the shit out of this Samsung and I used to have a 32" JVC. The sides aren't crooked or anything...I <3 my Flat CRT

[Prometheus]

So is it safe to assume this problem isn't fixable?

[ASSEMbler]

It's not worth the time or danger of fixing.

[Eviltaco64]

Try turning off velocity modulation, if possible. A lot of flat CRT manufacturers left this on by default because it helps in displaying a brighter picture, but it's known to cause some geometrical distortion.

Another late-gen CRT factory trick was to include a digital comb filter that can process and clean up the image. 'Warm' usually tried to process the image with more regard for the classic NTSC standard. 'Cool' makes for more vivid colors (and 480i component can actually look pretty stunning on some of those Trinitrons), but it is capable of calling out saturation and distortion in comparison. Turning it off completely usually makes it look more like 'Warm'.

[ASSEMbler]

Fiddle with all the knobs!

[TheRedKnight]

Try turning off velocity modulation, if possible. A lot of flat CRT manufacturers left this on by default because it helps in displaying a brighter picture, but it's known to cause some geometrical distortion.

Another late-gen CRT factory trick was to include a digital comb filter that can process and clean up the image. 'Warm' usually tried to process the image with more regard for the classic NTSC standard. 'Cool' makes for more vivid colors (and 480i component can actually look pretty stunning on some of those Trinitrons), but it is capable of calling out saturation and distortion in comparison. Turning it off completely usually makes it look more like 'Warm'.

A digital comb filter's purpose is to filter a composite or S-video signal. Basically it cleans up colour bleeding and other issues from those signals. Not really a "late-gen factory trick" so I wouldn't advice anyone to turn it off. I'm still using a TV manufactured in '93 because the digital comb filter in it actually does the job well. In my experience, later Sony Wegas (the silver ones that are way too overrated) don't even have a comb filter in them, but that's probably because I'm in PAL-land and RGB through SCART doesn't need that.

[Jamtex]

One thing no one has mentioned is that a lot of these CRTs are getting on for 20 plus years old, the speed bump issue can be a sign that the electrolytic caps on the board are drying up and not working as well as they should do. Replacing these could solve the problem as most arcade monitors I have that had this issue have been fixed with a cap replace.

[Prometheus]

Is there a way to test for sure? I have no idea how to work the inside of a CRT and I currently don't have the money to take it to someone who does.

[Eviltaco64]

A digital comb filter's purpose is to filter a composite or S-video signal. Basically it cleans up colour bleeding and other issues from those signals. Not really a "late-gen factory trick" so I wouldn't advice anyone to turn it off. I'm still using a TV manufactured in '93 because the digital comb filter in it actually does the job well. In my experience, later Sony Wegas (the silver ones that are way too overrated) don't even have a comb filter in them, but that's probably because I'm in PAL-land and RGB through SCART doesn't need that.

Thanks for re-iterating what I just said, but those digital comb filters can cause color bleeding of their own. It can make for a great picture (I use it on my own TV), but, especially when equipped with VM, it can call out a lot of distortion and bleeding that would otherwise be miniscule using a dimmer and more standard looking picture.

Above all, certain TVs look awful on their factory defaults. I'm only saying this because I had to adjust settings on my own overrated silver 32" WEGA for a few weeks until I found a combination that was versatile enough to handle what formats I threw at it.

[Prometheus]

So I just spent the last 4 hours testing out every option in the service menu, making notes of the original numbers to help ensure I don't screw anything up. Unless I miscounted, there were 294 options, and not a single damn one fixed my problem. I'd try to replace the electrolytic capacitors to see if that helps, but I'm not exactly an expert when it comes to the insides of CRTs.

All I want is a CRT with little to no geometry issues, ESPECIALLY no "speed bumps", and good color quality. Why is this so hard for me to find?

[Lum]

CRTs sold in the Americas were systematically crippled. I'm sorry but advocates of any TV type (CRT or not) who don't own a proper model have no clue what heck they're talking about. It's underestimated how bad of a limitation having composite/RF imposed on us for years was. In the infrequent event of correct geometry and color, our sets almost always still got no safe/simple way to even receive video as sharp as their CRT unit may be able to display.

[Prometheus]

So how exactly do I find one that isn't systematically crippled? As far as I know, CRT aren't sold as new anymore, so it's not like I can save up for one that catches my eye at a local electronics store. Would it be better to get a professional quality monitor (the ones with various inputs), or are those messed up as well? Assuming it's not, how would I even go about finding one?

This is all making my head hurt. Do I try to fix the one I currently have and risk wasting more money since it might not be fixable, or do I try to find a better professional CRT and risk wasting even more money if it has the same issues, or worse? I can't keep spending money on duds...

EDIT: I noticed something odd about the TV. Whenever I turn it on after being off for at least 10 or so minutes, the image on the screen gets incredibly bright (almost like the brightness settings shoots up to 150%, if that makes any sense), then darkens to normal after a few seconds. Is this a typical warm up period for some CRTs, or is something wrong?

Also, I noticed something else after my Xbox froze while playing an emulator. The screen is brighter in the middle than it is on the sides. In fact, it almost looks like where it begins to darken on the left and right sides is the spot it begins to "speed bump". There also appears to be extremely faint lines that scroll down the screen, almost like there is interference even though nothing else besides that specific TV suffers from it. Would these happen to have anything to do with my issue, or is this just a funny coincidence?

[lnx64]

I know what your talking about here.. I work on CRT's as a spare hobby.

You probably can see this effect in this video of my TV: http://www.youtube.com/watch?v=hE_VHAT15y8

It's a horizontal linearity issue. It's usually NOT the tube, because of the shadow mask really was so bad, it would have purity issues.. Instead the issue is that the yoke is speeding up and slowing down mid scanline..

You really are not going to be able to fix this.. Replacing caps is about all you can do, but if the TV did it new, nah, not worth the trouble..

Some TV's DO have a "H-Lin" control inside, that would help fix the issue, but not many have it..

As far as the speed bump being brighter or darker, yes, exactly what's going on here. When the yoke slows down the beam from moving, it compresses the scanline in that area, and thus makes the beam brighter.. Just like why if the vertical deflection collapses to a horizontal line, it really will burn the phosphors, for being far too bright..

To be brutally honest, it's not worth loosing sleep over. I've dealt with it for so long, I look at it as a characteristic.