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Old 2nd Jun 2022, 12:42 pm   #1
Retrorepair
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Default Sony PVM 2130QM - Dark picture, no colour on composite sources

So the 20M4U is off to a new home, hopefully someone with more time can fix it.

I got a 2130qm in part ex for it which I was told was fully working but of course, in reality it isn't.

So the image is very dark in both RGB and composite on any input. I have to turn brightness and picture controls all the way up in order to get a usable image, even then it could be brighter. The flyback is also turned up to just below visible retrace too.

Second issue, composite sources have no colour except a faint green vertical band about 2/3 into the image.

Third issue, NTSC (or 60hz) pictures have large borders and a bright line at the top. I assumed this was slight foldover, but saw on another forum there is an undocumented diode added to the reverse of the B board which I assume is a factory mod. This was totally rotten so I've removed it (almost fell off) and the image is now full height. I've no idea what the value should be though. When on a composite source and the VCR is playing a tape, on an unsynced image you can see the bright line is still there, just hidden in overscan.

I'm hoping once I've recapped it these issues will go away, but does anyone know of common issues for these or have any service notes?

Last edited by Retrorepair; 2nd Jun 2022 at 12:51 pm.
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Old 3rd Jun 2022, 3:19 am   #2
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Well I've replaced over 2/3 of the caps with what I had on hand and it's not made one jot of difference. All issues remain. I know I have a few to go but I'm not hopeful.

I think it's more than caps in all cases.

I forgot to mention the audio output is also dead, but I diagnosed that at least. The volume control IC is dead. Bridging it give me a nice, loud output so at least the amp is working and everything pre/post that IC is too. It's a TA7630p for reference.
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Old 3rd Jun 2022, 10:53 am   #3
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Some Sony monitors had the infamous green trimmer in the chroma circuit that caused no colour - there are usually a couple. Careful adjustment may well bring the colour back, but I'm not sure about the other faults.
Capacitor faults are rare on these.
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Old 3rd Jun 2022, 11:43 am   #4
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Thanks Glyn, that's interesting, I'll take a look. It does feel like it's just not decoding the chroma.

I was told that the PSU and deflection boards always need recapping on these, maybe that's not the case then. Still, these are well used 30 year old caps so it can't hurt to replace them I guess.

I do have a horrible feeling the lack of brightness is the result of a dying tube..
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Old 3rd Jun 2022, 1:55 pm   #5
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

No green pots that I can see on the B board and none of the pots that are on there seem to make any difference to the colours

Actually, I've just realised that on composite or rgb sources, the only front panel buttons that do anything seem to be the input selection. Picture, brightness, colour, tint, all look like they're working but don't affect the image at all.

Another thing I noticed, if I turn on 75ohm termination, the composite signal is reduced to a faint shadow.
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Old 3rd Jun 2022, 5:43 pm   #6
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Hi I would have not gone working through capacitors adlib as most of the ones used by Sony are very good. These monitors where very reliable. When Sky News first started they had a wall of 30 of them at the back of the news room, you would see them behind the presenters as the studio had a rear glass wall looking over the news room behind them, the wall of monitors being at the back. These ran 24/7. PVM2130's and 2730's where used by many television company's as studio floor monitors. I receive many queries about monitors, professional monitors like the one you had, 20M4 usually bought by retro gamers. Why these people think they need a 900 line resolution professional monitor for games that have about 250 lines of resolution I have no idea. If they want a good monitor I always suggest the PVM2130. Now capacitor faults on these are countable on one hand the main one that fails is in the frame stage C538, 680uF 25V. This is a special low ESR capacitor and I would fit a 65/100 volt rated device. When I change this I change C554 as well 100uF 35V. Now these have a multi-standard colour decoder PAL, SECAM, NTSC and NTSC 4.43 and they are not easy to work on as they are rather complex. I have had some small electrolytics give trouble but not many. You haven't mentioned weather this was a heavily used monitor or if it was relatively clean inside? Now to fix this set you will need a meter and an oscilloscope. First things first you did not mention if the "PAL" indicator lights with a PAL signal fed to it? and like wise a 60Hz signal should light one of the NTSC indicators. These do not suffer the subcarrier capacitor problem that other Sony's suffered. DO NOT TWEAK ANY POTS OR CAPACITORS!! you will never get it back without the proper equipment!! Now it looks like you've tweaked the G4 pot? which if nothing else will stop the video output stage biasing properly. To move on here you will need to measure all the tube pin voltages not G4 pin 3 which can be very high. You will need a good 1000V rated digital meter to do these measurements. Then feed the readings back to us. Another thing I would recommend to do on these is replace the dequsing posistor as they can go up in smoke when old and change C578 0.47uF 50V (line drive). I do use one of these monitors as my main workshop monitor and have had this since 1989. If you don't know anything about working with high voltages do not go near this, you have been told. Broadcast and to a lesser extent Professional monitors where looked after by highly competent engineers and due to this where paid much more than the average TV engineer.
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Old 3rd Jun 2022, 8:58 pm   #7
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

I second most of the above. And yes, these can be very difficult to work on when these kind of faults are present. Do you have a service manual?

Also, you clearly adjusted the flyback to see that it was already turned up? When the flyback lines appeares, were they also very faint and washed out or were they strong? My first thoughts are to think the tube may be worn out as these sets were very reliable. Any sign of any screen burn at all?
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Old 3rd Jun 2022, 11:08 pm   #8
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Thank you both for the advice.

Yes the retrace lines are pretty washed out when visible, I've a feeling this thing is just tired which is a real shame. Does a rejuvenator help much with Trinitron tubes? I've never used or even seen one to be honest, but I know their use has mixed results at best.

There's no way to set the colour drive on these is there? I feel if I could at least improve that as opposed to the cutt off I could get some more use out of it. I'll take a look at those areas Adrian, thank you.

I've a feeling I've got another lemon

I might add btw, yes I intend primarily to use this for games but also other analog video sources such as VHS and laserdisc. I realise it may seem overkill but really, if you can have the best, why wouldn't you? And old games look just stunning on these. Consumer sets are fine, but PVMs of pretty much any kind just look next level.
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Old 3rd Jun 2022, 11:09 pm   #9
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

No screen burn at all by the way and it doesn't look very used inside at all. Not nearly as much dust as I'd expect from a well used monitor. Hardly any really. It's a lot of issues for such a reliable unit though, no?
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Old 4th Jun 2022, 1:00 am   #10
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Attached are two images, one when displaying an image, the other when no source is selected. The latter really makes me think this tube is shot

This is in pitch black so maybe this is normal for these or just a bit of aging but it looks almost like there's a HV problem.
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Old 4th Jun 2022, 9:22 am   #11
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Looking like a worn tube, but don't give up yet. Everything else needs eliminating to diagnose tube is faulty. Is the B+ correct? As you say, a lot of apparent issues for a reliable set, but the lack of dust may just mean that it hasn't had a lot of hours, so don't give up yet.

I don't think it is possible to rejuvenate a trinitron successfully. I have never done it and there is lots of information about failures!
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Old 4th Jun 2022, 11:30 am   #12
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Quote:
Originally Posted by HurtyAC View Post
C538, 680uF 25V. This is a special low ESR capacitor and I would fit a 65/100 volt rated device.
In many modern low ESR or high ripple capacitor series, from a certain voltage up, a different electrolyte formula is used, giving a higher ESR. Depending on the series a 63V repacement might still be allright but a 100V or 160V replacement might be significantly worse. In short, there's probably no reason to go above 35V working voltage as long as you use a decent low ESR replacement.

This might have been different back in the days.

Last edited by Maarten; 4th Jun 2022 at 11:38 am.
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Old 4th Jun 2022, 11:50 am   #13
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Quote:
Originally Posted by agardiner View Post
Looking like a worn tube, but don't give up yet. Everything else needs eliminating to diagnose tube is faulty. Is the B+ correct? As you say, a lot of apparent issues for a reliable set, but the lack of dust may just mean that it hasn't had a lot of hours, so don't give up yet.

I don't think it is possible to rejuvenate a trinitron successfully. I have never done it and there is lots of information about failures!
Well the b+ was a little high at 136.6v but I don't think that's unusual. I trimmed it back to 135.5v anyway which is the closest I could get it.

Reading at the flyback, 200v is the same as the b+, is that right? 24v also is reading 0.014v so basically absent.
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Old 4th Jun 2022, 11:52 am   #14
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Soounds like the flyback isn't working at all, but that can't be since you do have a picture. Are you by any chance measuring on the flyback pins itself instead of after the rectifier diodes?
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Old 4th Jun 2022, 12:05 pm   #15
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Oops, yes your right. Been a while since I've done this!

24v is reading 25.29v and 200v at 211v
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Old 4th Jun 2022, 12:18 pm   #16
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Not totally sure the best place to be measuring b+ now. Which point should I look at?
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Old 4th Jun 2022, 12:40 pm   #17
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Check A1 feed diode and safety res, that trimer can be replaced by a fixed cap 22pf comes to mind or near.
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Old 4th Jun 2022, 2:55 pm   #18
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Which is the A1 voltage? I can't see it in the manual
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Old 4th Jun 2022, 5:00 pm   #19
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

A1 is the same a G2 in TV parlance. Just depends how old you are!! A1= first anode (screen grid), G2......screen grid. I use either term ....'Turn up the G2's' or 'Turn up the A1's'. I tend to use 'G2' for colour TV and A1 for B/W TV
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Old 4th Jun 2022, 6:30 pm   #20
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Default Re: Sony PVM 2130QM - Dark picture, no colour on composite sources

Ah ok, I think it was sitting about 560v when I checked. The service manual thinks anywhere from 220 to 770v is normal so seems about right since the screen volts aren't set to max.
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