Sony PVM developed issue with VHOLD latch

[mikeyp]

Hi, I have 2 9" SONY PVMs. When last used in 2020, they were both working fine. Yesterday, one worked fine, the other is latching its vhold in the wrong place. This is irrespective of console or input type. Adjusting the VHOLD knob will cause it to roll but will still ultimately latch in the same place. See photos for comparison. They are close in type but not entirely identical. The bagged one is in somewhat better physical shape too but this didn't seem to matter 3 years ago.

For reference, the good one in the bag is a SONY PVM-9045QM and the failed one is a PVM-9041QM.

Re. my skills, I'm not averse to measuring or soldering anything, dealing with sensitive electronics or high voltages so please don't worry about that. I'm just not familiar with these units and don't know what I'm looking for. Any help fixing it is greatly appreciated. 

Rear/Front


RGB Comparison


S-Video Comparison


Composite Comparison


(I need to post and see if I can fix the pictures as I'm not great at this)

[Jeff eelcr]

Although I have not seen these models, similar units have had bad capacitors cause these problems
also check for cold solder joints.
Jeff

[mikeyp]

Thank you. I was hoping to avoid generic "check all the capacitors" replies as this thing has ~150 of them and most of the unit is working fine. I don't think it's a cold solder joint issue as it's not something that's coming/going with vibration. I did try thumping it when you mentioned it but no change. It seems that the H/V Delay circuit is stuck for V delay at least. I'm hoping to investigate around here for something. There is some corrosion in this area too but hard to investigate.

I have found the service manual here: https://archive.org/details/sony_PVM-9041QM_9044QM_Service_Manual