WG K7000 problem

[Cisek]

 Hi
I just bought old K7000 monitor and have problem with v-position pot. It doesn't work at all, I can't center the image, which is a little too much on the bottom. Can capkit help with this?
The funny thing is when I first got my MK2 cab with Hantarex Polo with original chassis the v-size pot didn't work and I've got an overscan then I bought 8liners chassis and everything was ok except... h-position pot and jittering. Finally at this point another fail with k7000 and v-position pot.
Maybe something is wrong with my isolation transformer?
Additionaly I must replace flyback because something about 30 mins after booting cabinet the image starts to "jump" from time to time, but I quess it is becuse of monitors age.
Any advices would be great.

[Avinitlarge]

I would check the pot for damage 1st. I have a schematic if you need it. I don't think a cap kit will cure the problem though

[qrz]

all the v-pos ctl does is insert a dc voltage upon the vert deflection coil. usually half the supply voltage of the vert output IC
this will "bias " the on screen center point.

[Kevin Mullins]

So do you think possibly a low supply voltage on the vertical IC maybe?
In relationship to the B+ maybe?

We were just getting into this on another thread, I have one with the same issue, but hadn't really needed to look into it. (not noticeable while mounted in cabinet)

On the one I have it will shift off screen down, but not even to the top of the screen moving up. I believe his is the same scenario.

[Cisek]

I fixed it, thanks for the advices, just replaced the pot.