Sony PVM wavy edges

everten

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My PVM left and right edges start to get random waves in them after about 10 minutes of use. I noticed a hum coming from the monitor (power supply?) when plugged in and not even powered on. I switched to a different outlet and the noise went away, but the problem persists. Any ideas? Video here, pics below.

pvm1.pngpvm2.png
 

Nyder

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Is it happening on all inputs, is the DC hooked up via S-video?
Nyd
 

everten

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Is it happening on all inputs, is the DC hooked up via S-video?
Nyd

The DC is connected with S-Video. I have not tried the other inputs. I do have a VGA cable for DC coming in the next few days. Can I use a VGA to RGB to connect to the PVM on the RGB inputs with a DC VGA cable? Do sync cables need to be used if I do that?
 

skate323k137

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The DC is connected with S-Video. I have not tried the other inputs. I do have a VGA cable for DC coming in the next few days. Can I use a VGA to RGB to connect to the PVM on the RGB inputs with a DC VGA cable? Do sync cables need to be used if I do that?

Unless you have a VERY new PVM (like the 20l5) you cannot use a VGA signal (which will be 31khz) on the RGB inputs. PVM's typically only support standard resolution 15khz. I use the equivalent of a SCART cable for my dreamcast, which outputs the correct 15khz RGB for my PVM.

No idea what your issue is here though, sorry. The model number of your PVM might help.
 

everten

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Unless you have a VERY new PVM (like the 20l5) you cannot use a VGA signal (which will be 31khz) on the RGB inputs. PVM's typically only support standard resolution 15khz. I use the equivalent of a SCART cable for my dreamcast, which outputs the correct 15khz RGB for my PVM.

No idea what your issue is here though, sorry. The model number of your PVM might help.

It's a PVM 20M2U. I'll be checking the other inputs soon to see if I still get the waves.

So, if I get something like the Hanzo VGA box I could switch to 15khz and use the RGB?
 
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skate323k137

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It's a PVM 20M2U. I'll be checking the other inputs soon to see if I still get the waves.

So, if I get something like the Hanzo VGA box I could switch to 15khz and use the RGB?

Theoretically you should be able to use a Hanzo if you can get the right BNC breakout for it. Otherwise, dreamcast SCART cable to BNC breakout would work fine.

Reading up on some other threads, you might be looking at a re-cap job :( I hope you can get it worked out, that model is a really nice monitor.
 

everten

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Theoretically you should be able to use a Hanzo if you can get the right BNC breakout for it. Otherwise, dreamcast SCART cable to BNC breakout would work fine.

Reading up on some other threads, you might be looking at a re-cap job :( I hope you can get it worked out, that model is a really nice monitor.

Any guides around for re-capping one of these? I haven't done too much soldering. Maybe I'll crack it open and see how intimidating it is.
 

skate323k137

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Any guides around for re-capping one of these? I haven't done too much soldering. Maybe I'll crack it open and see how intimidating it is.

PVMs are pretty complex inside, lots of sub-boards. If money's not an issue I'd personally refer it to a qualified repair shop. Otherwise, you better be sure you know how to properly and safely discharge the monitor before you go poking around in it. There's a good chance any bad caps will be leaking or bulging, so if you know how to discharge the tube you might get lucky and be able to see what you need to replace.
 

everten

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So, it's not input dependent. The waves happen on all inputs. It also seems very random. I played on it for over an hour and never saw the issue. I play again the next day and it the waves start after 5 minutes and then went away after about 5 minutes of acting crazy. Still probably bad caps.
 

everten

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I finally got around to opening the monitor up. I played around with a potentiometer on the neck board (RV709). It fixed the problem for a few seconds. Not sure what this potentiometer controls, maybe horizontal width? Schematics are here. Page 69 shows neck board schematics (C Board).

The pot part info:
RV709 1-230-641-11 RES, ADJ, METAL GLAZE, 2.2M

Need to find a replacement part for this to see if replacing it will fix the issue. There is no info on wattage. Does wattage value matter in this case?
 

everten

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Played around with potentiometer some more and it does not adjust width. It seems to be a brightness or white balance? Turning it makes white become more yellow.
 

everten

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Recapped the power board and still having issues. Here is a list of caps on the power board if anyone is looking for it:

5 x 50v 10uf
3 x 35v 4700uf
2 x 50v 220uf
25v 3300uf
50v 100uf
50v 47uf
160v 1000uf
16v 3300uf
160v 47uf
35v 47uf
 

everten

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Here is a video of issue:

cbqA2V.gif
 

everten

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Might be a bad IC.

It seems to only happen when the monitor is warmed up. I can play for 20 minutes or so and then the screen width collapses and starts shaking. If there was a bad IC, wouldn't the problem always be present? I'm wondering if there are bad solder joints on the neck board or a bad transistor that is getting too hot.
 
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everten

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Found some promising info here. They were having almost the identical problem. It might be solder joints on the transformer.
 

Xian Xi

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It seems to only happen when the monitor is warmed up. I can play for 20 minutes or so and then the screen width collapses and starts shaking. If there was a bad IC, wouldn't the problem always be present? I'm wondering if there are bad solder joints on the neck board or a bad transistor that is getting too hot.

If it's a thermal problem with the IC then it would act just like that. When I repaired my mom's Wega, it did the same thing and turned out to be a custom IC in the TV. Had to order it off ebay, I think it was like $14 or so.
 

Pasky

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If it's a thermal problem with the IC then it would act just like that. When I repaired my mom's Wega, it did the same thing and turned out to be a custom IC in the TV. Had to order it off ebay, I think it was like $14 or so.

Sorry to stray a bit off topic, but do you know how to fix those white horizontal bars streaking towards the right of contrasted items on the WEGA's? My 27" is starting to do this more. Not sure what it could be. Hopefully you know what I'm talking about.
 

everten

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If it's a thermal problem with the IC then it would act just like that. When I repaired my mom's Wega, it did the same thing and turned out to be a custom IC in the TV. Had to order it off ebay, I think it was like $14 or so.

Reflowed solder all over the power board (transformer, connector pins, transistors, etc.) still showing issue after being turned on for 15-30 minutes.

Was the bad Wega IC on the power board or the main board? The only thing I see on the power board is a Sharp PC111 chip.
 

Xian Xi

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From what I remember it was on the board at the very bottom that sits flat that the fly back is connected to.
 

everten

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This thing is a beast, I wouldn't even know where to start looking for bad IC. Check it out (power board not shown).

15084374581_4844b98129_z.jpg


14900822127_00fd5499a8_z.jpg


15064386526_0bfcb2e9ef_z.jpg
 

K-2

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Aren't wavy edges on a CRT, typical of a bad filter cap in some cases, or even a the bridge rectifier? I.e. too much alternation of current when CRTs want steady DC...

I got this from watching those Peter Fromm lectures on CRT repair on youtube, but just an idea.
 

everten

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Tested voltages from power board to main board and found the -15V out measuring -20V and slowly climbs to to -25V or higher (didn't keep it running to see how far it would go). However, the -15V post on the transformer measures a steady -15V. Between the transformer and -15V out pin there is only a resistor, ceramic capacitor, and a diode. I removed the resistor, capacitor, and diode from the board and tested out of circuit and they appear good. The voltage increase occurs after the diode and ceramic cap, one end reads -15V and the other end reads -25V. Not sure if this is related to the issue, but seems odd.
 
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everten

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Huge thanks to wyo_vr4 for testing the -15v on a working PVM20M2U. Looks like the the readings of -20v slowly increasing to -25v are normal on the -15v circuit. The hunt continues...
 

wyo

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Huge thanks to wyo_vr4 for testing the -15v on a working PVM20M2U. Looks like the the readings of -20v slowly increasing to -25v are normal on the -15v circuit. The hunt continues...

Any time, brotha! :) Hope you can find the source of the problem.
 
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