WG 25K7197 issue adjusting full vertical height [fixed]

magicianlord77

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Hi, looking for some advice about this kind of issue I never had before, this is a 25K7197 monitor from a MK II machine I got that was in storage for too long, so before turning it on I replaced *almost* (more on that later) all its capacitors because they didn't look good.
After that I've put the monitor in the workbench and it works nicely, but I'm having issues adjusting the vertical height.
Turning the vertical pot from the remote, or the 50/60 HZ pot changes the vertical height, but at the same time the monitor slowly returns back to its shrunk size, displayed in the picture. It doesn't matter if I adjust it to be taller or shorter than that, it just returns back to that size by itself!.

I've replaced all capacitors minus the 10uF bipolar ones, because the ones I could get had more ESR than the originals. There were 4 of them, one in the add-on board and 3 (I assume for R-G-B) in the main board. Could the one from the add on board be causing the issue, or what else could I look for?
vertical-issue.jpeg
chassis.jpeg

Thank you!
 
Hard to say. Does it return to full size after you turn it off for awhile?
Nope, had it on from cold start for 15 minutes and it stayed the size of seen on the photo. Adjusting pots change height but in a matter of seconds it's back to that size by itself.
I think I'm going to check the 10uF BP capacitor from the P723 board that seems to be about "vertical linearity", not exactly related to the issue but the capacitor is old https://forums.arcade-museum.com/threads/k7000-with-p723.314461/
And also I guess R80 that is vertical height related - https://forums.arcade-museum.com/th...-size-with-pot-maxed-out.543469/#post-4976028 , I'll report back :)
 
Took out the chassis and began measuring components:
  • Q9 - good
  • C51 - good, 700nF ESR=7.4ohm
  • C13 - is a new capacitor, 22uF 63v - original was 25v I believe
  • R83 - it has two 680ohm resistors in parallel for some reason?
  • R80 - 2.2ohm
Then when handling the boards, noticed something on the remote pcb, V-SIZE pot (200ohm) is cracked.
Replaced it with a generic 500ohm one, bent the leads a bit to make it fit.
Now both the size adjustment and 50/60hz pot work perfect, so issue fixed, now I know :)

Thanks!

pot.jpeg
 
Took out the chassis and began measuring components:
  • Q9 - good
  • C51 - good, 700nF ESR=7.4ohm
  • C13 - is a new capacitor, 22uF 63v - original was 25v I believe
  • R83 - it has two 680ohm resistors in parallel for some reason?
  • R80 - 2.2ohm
Then when handling the boards, noticed something on the remote pcb, V-SIZE pot (200ohm) is cracked.
Replaced it with a generic 500ohm one, bent the leads a bit to make it fit.
Now both the size adjustment and 50/60hz pot work perfect, so issue fixed, now I know :)

Thanks!

View attachment 832104
whenever I work on K7000s with remote boards I unplug those and set them far away from where I'm working. those pots are unfortunately very fragile.
 
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