The WG 19K4600 on my test bench just started acting up last night. It was recapped about 2 months ago and has been working perfectly until now. About a minute after powered on, the vertical size starts changing rapidly. The image gets stretched out off the screen, then almost goes back to normal for an instant, and so on. Here's a video:
The B+ is measuring 127V and the vertical size pot VR302 tests okay with a DMM. Horizontally the picture appears stable, and there are no unusual arcing/snapping sounds when it jumps. If I put the Vert/Hor board from this monitor into another working K4600 I have, it does the same thing, so I'm pretty sure the problem is on the Vert/Hor board. I reflowed all the connections on this board, plus the daughter board headers on the main board. I'm not quite sure what to check next. Any suggestions would be appreciated.
The B+ is measuring 127V and the vertical size pot VR302 tests okay with a DMM. Horizontally the picture appears stable, and there are no unusual arcing/snapping sounds when it jumps. If I put the Vert/Hor board from this monitor into another working K4600 I have, it does the same thing, so I'm pretty sure the problem is on the Vert/Hor board. I reflowed all the connections on this board, plus the daughter board headers on the main board. I'm not quite sure what to check next. Any suggestions would be appreciated.

