Sony PVM display issue

[Retro Mecano]

Hello,

New to this forum, but my googling during past weeks led me here..

So i got a PVM 20M2E wich had some geometry and 3 Horizontal lines issue. Long story short i recapped the C585 and C572 as recommended in RetroTech videos.

The 3 horizontal lines disappeared. Did further adjustements in service menu, some focus pot tweak and the result was absolutly amazing.

Played happily my Snes through Scart/bnc for 1h or 2.. the the picture just disappeared.. sound still worked.

Restarted, changed the console, changed the input via component, composite, another cable, another machine..nothing. only sound.

Strange thing is that the menu still shows uo perfectly.
The Monitor seems to get a signal when powering on the console, but no display.
Here's what i did so far:

- I followed up the service lenu to reset each value to default.
- recheked all caps on PSU, Neck, Motherboard, I/O board.
- reflowed few solders even knowing they were fine..
- measured output voltage on PSU. Fine. Neck board. Fine..

Spent 2 weeks troubleshouting and i cant figure out what the f*** is going on.

Any help please?

Thanks

[Odyssey113]

Hello,

New to this forum, but my googling during past weeks led me here..

So i got a PVM 20M2E wich had some geometry and 3 Horizontal lines issue. Long story short i recapped the C585 and C572 as recommended in RetroTech videos.

The 3 horizontal lines disappeared. Did further adjustements in service menu, some focus pot tweak and the result was absolutly amazing.

Played happily my Snes through Scart/bnc for 1h or 2.. the the picture just disappeared.. sound still worked.

Restarted, changed the console, changed the input via component, composite, another cable, another machine..nothing. only sound.

Strange thing is that the menu still shows uo perfectly.
The Monitor seems to get a signal when powering on the console, but no display.
Here's what i did so far:

- I followed up the service lenu to reset each value to default.
- recheked all caps on PSU, Neck, Motherboard, I/O board.
- reflowed few solders even knowing they were fine..
- measured output voltage on PSU. Fine. Neck board. Fine..

Spent 2 weeks troubleshouting and i cant figure out what the f*** is going on.

Any help please?

Thanks

I'm not sure I have advice to offer as much as I would be curious to ask if you have a picture of these 3 horizontal lines issue? I recently RGB modded a 27S42 tv and I have an issue that sounds similar to what you're describing, having three horizontal lines across the screen, however the issue is very subtle and can usually only be seen on pure white or light grey screens. I've also verified that the issue exists even on my composite only signal so I can kind of assume it's not to do with the mod itself, although I honestly didn't test much on this TV before I modded it.

I uploaded a picture to show where the lines appear on my tv, just drawing in the location since it's hard to say i'll even be able to capture them on screen.

https://imgur.com/a/53zkoSf

I'm just trying to identify if my issue is a cap issue, since it sounded like that initially fixed your problem.

[fernan1234]

Strange thing is that the menu still shows uo perfectly.
The Monitor seems to get a signal when powering on the console, but no display.

Well the good thing is that you don't have a dead tube, and you still get a raster so that rules out a lot of things related to the neckboard, flyback, power.

Sounds like the issue is somewhere in the boards that process all the video inputs. Could it be that a bit of solder landed somewhere and caused a short? I'd do a careful inspection of the motherboard and I/O board, following the traces from the video inputs.

having three horizontal lines across the screen, however the issue is very subtle and can usually only be seen on pure white or light grey screens.

If you were only talking about two lines, and especially based on your picture, I would be sure it's just the two damper wires that hold the aperture grille and which are totally normal on Sony/Trinitron tubes. But no idea about why you see a third line across the middle. Either way, that's a totally different matter from the "three line" problem TC had which is three R G B lines that appear on the effective area and with varying distance between them around the top part of the screen, and they're always a sign of failing caps. Normal behavior is for those lines to be close together and in the overscan area.

[Retro Mecano]

I had the same thought actually, so i already checked the coonnection on the motherboard nearby I/O board, and they where fine, no shorts, no extra soldering etc.. i even went to dissolder the whole I/O pcb from the shield and inspect inside for the same problems.

Everything was fine.. my problem is that i dont know how the video input is processed through the chips. There's a lot of them and cannot figure out how to follow up the signal at least with my multimeter. Sadly i do not know how to handle (yet) an oscilloscope and i dont have one.

[Retro Mecano]

It's 2025 and i didnt manage to repair the pvm..
Everybody adviced me to go in here hoping to get advice.

The monitor is collecting dust since 2 years.

Any veteran here willing to revive the thread and monitor?

[SuperSpongo]

Have you picked up a scope over the years?
I would approach the error by checking the service manual's block diagram. I agree with the previous poster that there seems to be something wrong in the signal path. But since you checked all signal types and don't even see a garbled picture, maybe some kind of protection circuit triggered and blanks the whole picture but not the menu (X-Ray protection maybe?).
I would again check the service manual for protection circuits and see if the video signals make it through the signal processing boards (this would require a scope and possibly soldering probe wires).

[Retro Mecano]

Have you picked up a scope over the years?
I would approach the error by checking the service manual's block diagram. I agree with the previous poster that there seems to be something wrong in the signal path. But since you checked all signal types and don't even see a garbled picture, maybe some kind of protection circuit triggered and blanks the whole picture but not the menu (X-Ray protection maybe?).
I would again check the service manual for protection circuits and see if the video signals make it through the signal processing boards (this would require a scope and possibly soldering probe wires).

Sadly didn't grab a scope and don't know how to use on (yet).
i'll start may be with your suggestion to check Service manual for protection circuit. it's hard to find out as the Ic's and their role are not really well identified in the manual.

[SuperSpongo]

it's hard to find out as the Ic's and their role are not really well identified in the manual.

I just thumbed through the manual on archive.org
https://archive.org/details/SonyPVM20M2 ... 7/mode/2up

Page 38ff has a block diagram which also identifies the ICs and their respective functions. (IC101 Microcomputer, IC104 On Screen Display, IC105 DAC and so on). Later in the manual, you can also see what they're supposed to look like.

It's all quite tedious, but worth a shot. There are some service manuals where Sony included detailled explanations of the various circuits, but sadly that's not the case here.

EDIT: One more thing: If you want to work with the online service manuals, you should manually stitch the photocopies of the large pages together (I use Gimp to import the pages of the PDF and overlay them). This is also tedious work, but you will go insane tracing the lines of the diagram and having to jump to another page.

[Retro Mecano]

it's hard to find out as the Ic's and their role are not really well identified in the manual.

I just thumbed through the manual on archive.org
https://archive.org/details/SonyPVM20M2 ... 7/mode/2up

Page 38ff has a block diagram which also identifies the ICs and their respective functions. (IC101 Microcomputer, IC104 On Screen Display, IC105 DAC and so on). Later in the manual, you can also see what they're supposed to look like.

It's all quite tedious, but worth a shot. There are some service manuals where Sony included detailled explanations of the various circuits, but sadly that's not the case here.

EDIT: One more thing: If you want to work with the online service manuals, you should manually stitch the photocopies of the large pages together (I use Gimp to import the pages of the PDF and overlay them). This is also tedious work, but you will go insane tracing the lines of the diagram and having to jump to another page.

yes i was also taking a look at the exact same diagram. that will need a lot of testings.. i will take the risk and the time needed doing it.
by the way, the monitor had another issue from the beginning which did not affect the set. if i press the "blue only" button, which i supposed to drive the blue gun only for testing purpose, brightness immediately rises and then monitor shuts down with tally light. it will power on again after disconnect and reconnect from wall outlet. some kind of power surge. other then that it works fine if i don't turn that "turd" lol. any idea where to look at?

[SuperSpongo]

Never heard of that before, sorry.