PVM Color Loss

[Cj1]

My PVM only displays in Black & White over Svideo/Composite. However, RGB works fine. I was advised this can be an issue with the color demodulation, which is controlled via the B board on my unit. Im not quite sure what to look for as i dont see any obvious signs of damage or broken solder joints. Is there an IC i should replace or should i just do a full recap of the board and hope for the best?


https://archive.org/details/SonyPVM20L514L5ServiceManual

[Runco990]

I'm not going to look through the manual, but I can offer some suggestions based on hundreds of Sony monitors I serviced.

You are sure it is set to the right standard?  NTSC PAL Secam? 
Obviously not in "blue only" mode....
And finally, before going nuts, I have seen this in PVM's many times, check the color oscillator trim capacitor.  I have had this issue MANY times, but mostly in the small 80 series PVM's.  A tiny nudge of the color oscillator trimmer would pop it right back in.

And... the "L" series does suffer from leaking capacitors.....  yep...

Hope that helps before you dig in deep.

[Cj1]

I'm not going to look through the manual, but I can offer some suggestions based on hundreds of Sony monitors I serviced.

You are sure it is set to the right standard?  NTSC PAL Secam? 
Obviously not in "blue only" mode....
And finally, before going nuts, I have seen this in PVM's many times, check the color oscillator trim capacitor.  I have had this issue MANY times, but mostly in the small 80 series PVM's.  A tiny nudge of the color oscillator trimmer would pop it right back in.

And... the "L" series does suffer from leaking capacitors.....  yep...

Hope that helps before you dig in deep.

Yes, its on NTSC with an NTSC source. Blue only is off.

I know the 8" series had a service bulletin to replace the trimmer pot, however i wasent aware the L series had any trimmer pots as everything appears to be digital. I do see what looks like adjustable resistors on the B board, not sure if thats what you mean?

https://imgur.com/a/K7MfJyw

[Runco990]

Not sure... I have not worked on a lot of L models to be that intimate with them.  See if you can find where the 3.58mhz crystal comes from and it's on frequency.  This setting could indeed be "way off" in the service menu.  I haven't worked on these in a long time, so have forgotten a lot. 
Do check these things before suspecting worse problems.  I have seen monitors where someone screwed up the service menu setting to write off the monitor as broken.  Quite a few times.

Of course you failed to mention if you GOT it that way or you owned it and this just happened by itself.

[Cj1]

Not sure... I have not worked on a lot of L models to be that intimate with them.  See if you can find where the 3.58mhz crystal comes from and it's on frequency.  This setting could indeed be "way off" in the service menu.  I haven't worked on these in a long time, so have forgotten a lot. 
Do check these things before suspecting worse problems.  I have seen monitors where someone screwed up the service menu setting to write off the monitor as broken.  Quite a few times.

Of course you failed to mention if you GOT it that way or you owned it and this just happened by itself.

I received it this way. I was actually able to borrow a working unit from a friend and swap the boards. The problem goes away when i swap out the B board, however I am not quite sure what component could be causing the malfunction.

I suspect it may be a problem with one of the control IC's, however I think those need to be programmed and arent really replaceable.