I have a Wells-Gardner 19K4675 that the Verticle center will not adjust. I can move the Yellow wire to any position and it stays the same. Monitor has just been capped.
Have you checked for cold solder on the bottom of the board in that area? I had one come in the other day that had a permanent jumper soldered on the bottom....
I reflowed all the header pins when I recapped it. Everything looked good in that area. Anyone have a Star Tech Journal Volume 14 Issue 3 there should be a article on this problem?
I just checked it out. Moved the ground = No change.
Checked R352 (15K resistor) and it had a reading of 14.82K = it's good.
There are factory jumpers on the bottom of this board. The yellow wire for vertical center connects to a resistor and the other side of the resistor has a jumper going to J28 Pin 1 of the X/Y board.