Screen flickering yellow/warmer on PVM...

[ajdesmarais]

Hoping someone here has experienced this problem. I'm the new owner of a Sony PVM-20M4U. It's a great unit, but I only just noticed an odd problem it has. The picture will intermittently flicker to become yellowish/warmer, as though it's trying to correct its own temperature. (It does not seem as though I am completely losing a the color blue, which will also make the screen look yellow. Blue is still there, but the screen is tinted yellow over it.) Sometimes it will stay this way, other times it will not. Turning the TV off and then back or, or degaussing does not affect it, but restarting whatever video game system I'm playing DOES reset the effect, if only for a little while. The issue does NOT occur when I am using the TV in component mode, or at least I haven't seen it do so.

This leads me to believe it may be a problem with the SCART to BNC cable I'm using. I've got another one on order to try it out, but in case that doesn't work, I thought I'd come here and ask. Also, I took a picture of the phenomenon to compare. Correct colors on the left, yellowed on the right. Obviously. Thanks in advance!

[Gered]

I had a similar looking problem a while back and in my case it did turn out to be a problem with the SCART to BNC connector I was using. Your problem really sounds exactly like mine, with the intermittent flickering, etc. When I opened the SCART connector part up on the cable I could see the RGB red wire had mostly come loose (looked like a poor soldering job to me), and I guess occasionally was shifting position and losing connection / making a poor connection depending on if I accidentally shifted the cable around if I was moving anything else close by and knocked it or something.

Bought a new cable (at the time I did not have a soldering iron handy to try to fix myself) and that fixed the problem.

[ajdesmarais]

Well that's cool. I did crack my cable end open to see if anything was wrong, but I didn't really notice anything, nothing seemed loose. Hard to tell, a lot of it is covered in hot glue. I didn't think to try jiggling the cable around to see if it made a difference. I was hoping it wasn't anything with the monitor itself. Even though it's almost 20 years old, according to the guy I got it from, it has actually seen very little use. Oh well. The cables should be here this week, so we'll see.

[Gered]

I guess also worth mentioning is that I also noticed the exact same intermittent flickering problem when using one of these. I didn't jiggle/bump that part of the cable very often, but when I went around dusting I would bump it sometimes I guess and when I'd go to play something hours later I'd notice the flickering issue. Took me a while to put two and two together in my head and realize what the cause of the problem was. Now that I took that out of my setup (wanted the audio breakout for something, now using RCA Y-adapters instead) the problem is gone (again! heh).

[ajdesmarais]

Thanks for the input, it was hard to find someone who had the same problem as me.

I ended up putting my old cable back on and jiggling it around a bit after disassembling and inspecting. With certain movements, it's very easy to get the blue signal to ground out completely. I'm assuming there might be a fray or a kink somewhere in the length of the cable that may be causing the flicker. I have another one coming in today, so I'll test it out and hopefully the problem will be resolved.

The "defective" cable came from retrogamingcables.uk, while my replacement was ordered from wookiewinn on ebay, in case anyone wants to know.

[Taiyaki]

I believe I had that same problem before. I thought it was the switch box at first then the cables but nothing would fix it until I finally found that the true culprit was the rgb analog board, the board where you connect the bnc for rgb sync (not sure on the PVM but I think on the BVM it's the second slot next to the ISR slot board). I replaced that and it never happened again. Not sure what the cost is for your unit but for comparison's sake the BVM boards were generally available on ebay at the time for roughly $50.

To describe what my issue was:
From time to time the picture would fluctuate to a warmer tone, sometimes it would be of slightly different intensity, it would also sometimes correct itself but potentially reappear. On lucky days it wouldn't happen at all.

The problem would not go away by powering off the tv. It would go away if I powered the console off.

It looked pretty much like what you have in that picture. I'm rather confident that replacing that board should fix it if you have the same problem I had.


Wookiewin is awesome, his cables should definitely fix it if the cable is the problem.

[Gered]

The "defective" cable came from retrogamingcables.uk, while my replacement was ordered from wookiewinn on ebay, in case anyone wants to know.

It's interesting you mention this, as this is exactly the same as me. However, I also have a SNES MultiAV -> SCART cable from retrogamingcables which works perfectly, so could just be one of those things... *shrug*

[Ed Oscuro]

When did you order the cables from retrogamingcables?

We've had reports of bad design from them in the past, but of course this could just be random per-unit quality variation, or even rough handling from the post office, depending on what the failure is like.

Still, it seems like the old suggestion to buy from Retro Console Accessories, or maybe some of the other suppliers (I've never heard of wookiewin before now) are still sensible.

[Gered]

I bought mine around March last year, and it worked fine for 6+ months before I saw any signs of problems. I like to think I was not particularly rough with it (I may have accidentally lightly bumped the cable once or twice before first noticing any problems with it, but certainly nothing major), so either an issue when it was made, or as you say, some rough handling during shipping.

I know this probably doesn't mean much either, but the SCART->BNC adapter from Wookieewin does feel like it's more "solid" just when handling it / looking at it. Same kind of feeling I get when looking at a retro_console_accessories SCART cable vs a retrogamingcables one. But I've never opened both up to compare, so yeah, not any kind of meaningful comparison for sure, heh.

Definitely interested to hear back from ajdesmarais about whether the new cable fixed his problem though.

[ajdesmarais]

When did you order the cables from retrogamingcables?

Sometime in late November/early December 2015. I was going to pick up a replacement from Retro Gaming accessories, but her store seemed like she was in the middle of a restock. Wookiewinn had the cable, and both they and retro gaming accesories claim to use full shielding and double grounding, which retrogamingcables.uk does not.

Definitely interested to hear back from ajdesmarais about whether the new cable fixed his problem though.

So far, so good, although the problem didn't always manifest itself immediately. Sometimes I could play for almost an hour and not have an issue, and I don't have that much free time during the week. Hopefully this weekend I can sit down and have a nice, lengthy session or two and see if the problem has been cleared up. It's going to be nerve-wracking, because if the problem IS still there, it means it's definitely in the monitor, AND I've been wasting money on extra cables.

[ajdesmarais]

I finally found that the true culprit was the rgb analog board, the board where you connect the bnc for rgb sync.

Interesting. I secretly fear this is still my problem. Unfortunately, the RGB board on a PVM isn't built to be swapped out like on a BVM. I did have the set apart, and it seems like it wouldn't be too hard to replace at all, the problem would be finding one.

At that rate, I may just go for another monitor. I've got a bead on a couple of 20L5s, which I really want for 480p stuff. I got my current PVM for free, so I suppose I ultimately can't complain.

[ajdesmarais]

A little research through my parts manual reveals the RGB/Component terminal board (Q) for a PVM-20M4U is part number 153773514. A little more research indicates they are next to impossible to come by, and the one website that DID claim to have them in stock wanted over $500 for them.

I suppose I can always pull it and inspect some capacitors or try to replace them. Just annoying, I've spent infinitely more time searching for and troubleshooting this monitor than I have actually using it.

[Gered]

I've spent infinitely more time searching for and troubleshooting this monitor than I have actually using it.

I think for some people that's the fun part, heh. But yeah, I totally get your frustration. Hopefully after you get more chance to play some games over the next while you don't notice the flickering anymore with the new cable and then don't have to do any more troubleshooting.

[Taiyaki]

If your PVM is good other than for that one problem then you could search for an identical model and just swap that one board. In my case there were no bad capacitors or transistors that I could see, but I'm not an expert either. I just replaced it and it never happened again.

[ajdesmarais]

I thought about that, but really, if I'm going to put the effort into finding another monitor at all, I should just get a 20L5 for 480p, which I will definitely use.

Anyway, I've been playing my SNES for over an hour and haven't noticed anything, but I'm still not convinced. More testing is required.

[ajdesmarais]

Update: It took another hour of playing, but the problem came back, so it wasn't the cables. Looks like I'm gonna be hunting down another PVM, I guess. Dammit. Thanks to Taiyaki for helping me isolate the issue.

Although, both RGB and Component signals pass through that board, and I have never had this problem with anything hooked up via component, even after playing for hours. Does this mean that the problem might be deeper? I imagine there is some different circuitry involved in processing the component image as opposed to RGB, but is that circuitry located on the input board or on the main board?

[Taiyaki]

If you manage to pass through another signal without problem it's most likely because the signal goes through either a different board or a different section of the board. Now that I hear your test results I'm quite sure the problem is the same I had which is the rgbs portion of the board (which in the BVM's case, was that entire removable board) being faulty. If you can examine it closely maybe you'll spot something wrong. If like in my case, you see nothing wrong anywhere, then I think it's a bit problematic to fix really. Maybe with some luck some expert repair / modder with some experience with these units can advise.


For what it's worth I would stick to component. I actually can't see much difference between component and rgb and I'm quite ocd on picture quality really.

[ajdesmarais]

For what it's worth I would stick to component. I actually can't see much difference between component and rgb and I'm quite ocd on picture quality really.

That's all fine and good, but none of my other systems output component. I suppose I could look into a trans-coder of some kind as a stop-gap solution. I think I'll keep my eyes open for a better model.

Also, I took my monitor apart again to inspect the terminal board. It's not terribly hard to get it out, but you can't really do any inspection on the board without de-soldering every single connection on the board, because the ports are all bolted through the rear plate from the inside, and then soldered onto the board, and the board and plate are soldered together as well. It wasn't designed to be a serviceable unit, apparently. Just a warning to anyone else who might try the same thing at some point.

Thanks for all of your help!

[Taiyaki]

For consoles that don't output component you can still use the scart through one of those YUV encoders and hook it up via component. My problem with those is that they run a little hot even when not in use, at least the one I have. Still might be worth it if your tube is in good condition aside from the rgbs connection problem. Picture quality would really not suffer imo.

If looking for a new tube is what you'd prefer than I wish you luck in finding a good one to your liking without issues (it's tough, I totally understand).

[blackoak]

Just a bump here. I had the exact same problem as OP with my PVM 20M4J. Found another one online, swapped the RGB input board (the back panel), and it's completely fixed. Easy swap too for anyone with this issue.

Now my question is, can the problem RGB input board be fixed? Would it likely be a bad/leaky capacitor? I can take pictures of the board if that would help with a diagnosis.

Also, out of curiosity, is this a known problem on other PVM models?

EDIT: looks like the metal shielding and BNC connectors are welded to the board in such a way that desoldering everything might not even be possible, or worth the trouble. i don't see any blown caps either, hmmm...

[cloudstrifer]

Same problem, same solution, rgb/component board swap and success.

Green and bright screen after random minutes, sometimes it blink too.

Thank you!