Weird issue with PVM-14M2U going gray

[squirrel-chan]

Hey all.

I posted this on reddit a few days ago and didn't get much info, I have an issue where a 14M2U I just got stopped working one day later, there's a good image for a few seconds before it slowly wipes into a grey mess for the signal and green for the OSD. The OSD is still very clearly visible, no distortion or brightness dipping. The video signal is completely lost in a gray mess.
Original thread: https://www.reddit.com/r/crtgaming/comm ... or_reason/

Here's a short video of the issue happening upon power on, signal is 480i Wii Composite but this happens regardless of input.
https://computerfairies.s3-us-east-2.am ... cfa1f9.mp4

Here's a picture of the OSD while the issue is occuring.
https://i.imgur.com/H9R9yrf.jpg

Following reddit's advice, I've emailed savon-pat about this issue, detailing it in a few paragraphs, only to be met with a single-line reply: "bad CRT".

I'm still not fully convinced though, and wanted a second opinion here. Wouldn't a bad CRT display garbage regardless of signal? Why is the OSD clear in green if the same white tones don't become green in a video input? This led me to believe it could've been something bad in the A board near where OSD generation is made. I've managed to open the whole monitor up and visually inspect it, I've found a few non-Nichicon or Rubycon caps, one of them looking slightly bulgy but not vented, and replaced them, but didn't have time to do a full recap by hand just yet.

Well, after putting it back together there was absolutely no change to the picture, but at least I didn't damage it further.

So I wanna hear from you, do you think it really is the tube and this is hopeless, or is it some component I could feasibly swap out? I can still return this monitor to the shop I got it from and wait for another 14inch to appear, but given the rarity here and how fond I grew of this monitor during the brief time I had it working, I'd like to get it repaired instead.

[gray117]

Often broken picture but working osd is attributed to something relating to control grid (G1) or screen grid (G2)

Given the way the grey kind of scans in it would seem to be related.

The good news is probably this isn't something corrupt/broken chip wise (a video process or alignment chip for example) since this wouldn't work + fail, it would just be broken permanently. But instead hopefully it could well relate to a failing part on a component that is common to all inputs (cracked trace/cap/resistor being the more common suspects).

... Unless there's a dying capacitor and/or resistor that can be identified the G1/G2 route will likely lead to essentially fiddling with flyback transformer to correct voltages - not generally recommended unless you know what you're doing - I say fiddling there will be proper measurable values, but usually at this stage most people are probably ditching the set or replacing parts... Never gone down this path myself... SO please take the following as a best guess:

Unless you pursue some kind of professional/more informed repair I'd perhaps just just try i) replace what caps you can ii) replace what resistors you can ... and at any stage perhaps see if the flyback is adjustable at all whether varying that changes the effect or not - even with fixed components the flyback transformer itself might be struggling/different/failing... If nothing seems to change the behaviour ... er ... original diagnosis probably stands

[xAzurexEonx]

I agree with gray117.

Being that it does display before it goes to the gray screen it's more likely something going bad rather than it be something dead/broken.
Caps, resistors, visible damage check.

However it is very tough to advise since we are unaware of setups. Have you terminated your BNC outs? Many people end up having weird things happen since they never did, and it worked without before, but suddenly the PVM cannot handle with the terminators.

I only mention the above incase you did skip any steps in proper setup (even if anyone has had a setup work for a good while), that could now be giving you issues.

[squirrel-chan]

However it is very tough to advise since we are unaware of setups. Have you terminated your BNC outs? Many people end up having weird things happen since they never did, and it worked without before, but suddenly the PVM cannot handle with the terminators.

My setup is quite simply only a composite input in either line A or B, I don't have any RGB cables or BNC terminators yet. Do you really think the terminators would make this huge of a difference? It doesn't matter which input you have enabled on the PVM for this issue to happen.

I'll be opening the PVM again with a friend today and giving it a more thorough check for damaged components and focusing more around the FBT this time, whereas before I focused on the RGB out part of the board. Since I only have a soldering iron and not a desoldering gun, a full recap will take longer than a single afternoon, I'm afraid.

[xAzurexEonx]

However it is very tough to advise since we are unaware of setups. Have you terminated your BNC outs? Many people end up having weird things happen since they never did, and it worked without before, but suddenly the PVM cannot handle with the terminators.

My setup is quite simply only a composite input in either line A or B, I don't have any RGB cables or BNC terminators yet. Do you really think the terminators would make this huge of a difference? It doesn't matter which input you have enabled on the PVM for this issue to happen.

I'll be opening the PVM again with a friend today and giving it a more thorough check for damaged components and focusing more around the FBT this time, whereas before I focused on the RGB out part of the board. Since I only have a soldering iron and not a desoldering gun, a full recap will take longer than a single afternoon, I'm afraid.

As I said, I only mentioned it in case it was a possible issue via BNC, colors and signal errors have been reported without using them.

Input A and B do have outputs that could be terminated, but I never heard anyone needing too.

In any case, I hope once you get it open it'll be an easy spot.

[squirrel-chan]

So I got the monitor open right now and we decided to test the voltages coming from the PSU (board G)...

Can't find much info on the readings other than the 115v one from the service manual, but, -15v is reading, without a load, -22v. Is this normal? The boards also seem a little reworked, but I can't tell to what end or whether or not they came like this from Sony. Can't imagine Sony would do this mess of a job...

https://imgur.com/a/6UEkd

EDIT: Oh yeah, and also, the -22v line took much, much longer to dissipate than the other 3 (5v, 15v, 115v)

[xAzurexEonx]

If a professional shop opened it up, there usually will be some sort of sticker with their info on the metal housing inside. All monitors I've ever gotten had them. That rework looks exactly the same as one of my 20M4Us.

Wish I had more in depth info about what ranges ought to be. Whenever I worked on these I just narrowed what issue I was having and only worked on those caps/traces. Dissipation can vary by quality and age, so if you feel it's far out then replacing will not hurt.

[squirrel-chan]

Couldn't see any sort of sticker saying anything about the rework. It doesn't look new either but upon further inspection it might've come from factory like that. I just wish I knew what that piggybacked cap and jumper wires are trying to accomplish...

Given the other output voltages are fine, I think the -15v being too high might be one of the faults with this monitor, but I couldn't put my finger on what part of the power supply is bad. All electrolytic caps look fine, none are bulged or leaking. Might need a more experienced tech's hand on this...

[xAzurexEonx]

Yes very possible that these boards were factory and all of mine that have been opened had other work done aside from we are seeing.

If you have any luck please keep us posted.

[squirrel-chan]

I've got midterms next week so I won't work on this right now but after next week I'll try recapping the PSU (board G), failing that, I'll send it off to a professional.

[AndehX]

Just curious, whats the best method for replacing capacitors in these monitors? I'm thinking of doing the same to mine. I can't find a definitive list of caps for the specific boards in my monitor, so would best thing to do, be to simply map out all the caps on a piece of paper, remove them all one by one and record their values, then simply order replacements? I figured without a definitive list, this would be the best option...

[xAzurexEonx]

Just curious, whats the best method for replacing capacitors in these monitors? I'm thinking of doing the same to mine. I can't find a definitive list of caps for the specific boards in my monitor, so would best thing to do, be to simply map out all the caps on a piece of paper, remove them all one by one and record their values, then simply order replacements? I figured without a definitive list, this would be the best option...

At the end of the service manuals there is a list of components and their locations. So lets say you remove something off the board labeled TN601, the manual will have what is suppose to be there.

The only issue is you may run into custom Sony components that you'll have to google to find a cross-reference for, but doable.

[Syntax]

Buy a can of freeze spray and start spraying the areas you think may be stuffed while the screen is powered on.

Because it works then fails there is a good chance a component is heating up and failing, cooling said component will cause the picture to rectify somewhat and help find the cause of your fault.

Keep in mind this is more for finding faulty resistors. It does not work so well for electrolytic caps.

[squirrel-chan]

Hey all, a bit of an update.

I've replaced most passive components (caps and resistors) in the -15V line that I could find, including the photocoupler in that board. So far, no luck
It still measures -17V under no load and -22V after plugging the CRT in, turning it on, back off, and measuring the -15V output. (The other outputs have already bled out by this point but the -15V still measures -22 and very slowly decreasing over a few hours.

So I'm not sure what to do at this point, I guess I can either keep at it (diodes? there's a zener ref voltage diode for the 15V line... but it's not for the -15V line, and the 15V line is fine...) or send it off to get repaired. Only I'm not sure who I could send it off to.. and I'd rather only get the PSU looked at, without having to move the whole monitor, wonder if any place here would take that...

Here's the PSU schematic (too big for an embed), stitched together from being spread across 2 pages in the scanned PDF for the service manual for this monitor.

Anyone's got any clues I should pursue before sending it off?

[squirrel-chan]

So I stuck a voltage regulator in the -15v line but that didn't help it..

Do I rule out the PSU now? What else should i look for? Do I do a full, full recap of the A board? Or is there something more specific I can look for?

I'm out of ideas...

[xAzurexEonx]

The only thing I can think of is the crt gun isn't working properly. The "rolling away" it does is the left to right sweeping frequency.

It could very well be a bad crt OR something eventually failing and stops sending the proper info to the gun/tube components.

It wouldn't hurt to recap vs cost of replacing.

[treminaor]

Sorry to resurrect a dead thread but I have almost the same issue as OP with another 14M2U. Instead of a gray screen, this one no longer can sync a signal. Not even composite. The picture is always rolling and garbled, and displays NO SYNC on the screen info. OSD works fine.

The reason I say my issue is similar is because I have the exact same symptoms with the power board (G board). The -15v line is high at -22v and slowly climbs by 0.01v while the monitor is powered on, regardless of if the A board is connected or not. I watched it climb all the way to -24v before shutting it off. After shutoff it takes an EXTREMELY long time for that voltage to dissipate. It goes down by 0.01v every 30-60 seconds, I would estimate a full discharge would take hours.

Another clue is there is ground noise that I can observe with an oscilloscope at all ground points of the boards... so something is leaking current to ground. I'm guessing something on the -15v line is shorted to ground because of a dead component. If I remove termination from the input signal by grounding the output BNC terminals, the picture is no longer garbled and just continues rolling because of the lack of sync. I think the ground noise is garbling the picture and something on the sync circuit is dead/not powered.

OP, did you ever find more information about your issue? Does my additional information give a clue as to what could be wrong? My plan of action is to follow the -15v rail on the G and A board schematic and see what components are connected.

[MKL]

The -15V supply doesn't seem to be used at all so it's normal that without a load it goes up and takes forever to discharge.