PVM-20M4U Capacitors / Service Manual Discrepancy

[eccoboy]

I'm replacing all capacitors in a 20M4U and found a capacitor value mismatch between the current one and what is in the service manual parts list and schematic diagram. I am tempted to go with the value listed in the service manual but I also see a discrepancy between some of the connections around this capacitor. I haven't been able to determine the function of this section of the board so I'm looking for any advice someone may have. Thanks

[Dochartaigh]

I can't say what the best course of action is for you, but I can tell you I've seen this on occasion. There were commonly design revisions through the years (which may not be shown in the specific service manual you have), and things like service bulletins which said to replace a certain part (or parts) with a part(s) with a different value than they originally used.

[eccoboy]

Ok that makes sense. Too bad the manual isn’t dated to give me a better idea of which value/design is more recent. And it looks like service bulletins aren’t easily attainable.

[Xer Xian]

Another guy found the same discrepancy in his 20M4A, as documented here: https://www.retrogameboards.com/t/honey ... ce-log/852 (very detailed log, well worth checking). He seems to imply this model came out of the factory with the wrong caps (post 20), but he doesn't elaborate much on it.

[Ed Oscuro]

If it ain't broke...

I did a cursory search for service bulletins, and found a post by Dochartaigh on reddit about C584:
https://www.reddit.com/r/crtgaming/comm ... m4u_recap/

Nothing about C1382 shows up. Maybe ask Pat Savon?

@ Xer Xian: I found this in the link you posted:

UPDATE:

Regarding mismatched capacitor at location C584:

It appears there was a service bulletin for various PVM’s like mine that states that you should replace C584 (2.2uF) with 1UF high ripple capacitor. So the capacitor that is already in there is correct.

Reference link: https://www.reddit.com/r/crtgaming/comm ... m4u_recap/

Which links back to the reddit post above. Didn't see anything about c1382. This seems like a different issue to me.

[eccoboy]

I saw the retrogameboards site but since my PCB doesn’t match the service manual schematic, I’m sticking with the original value capacitor. My monitor looks great but I need to replace 584 to fix the issue with lines at the top of the screen. I decided to replace all capacitors at the same time since others reported increased brightness after doing so.