Wells Gardner K4900 picture offlimits, cant center it. please help

[abispac]

So i got a generic cabinet that came with an snk neogeo system without a cart, and what according to this link https://forums.arcade-museum.com/threads/ms-pacman-restoration-part-3.405826/ looks like an k4900 wells gardner monitor. Now i scraped the neo geo, but before that, i borrowed a cart and tested it. The image looked off limits , as you can see on this image

the credit are outside or as i call it, offlimits, you can also see here

the image its not centered either. Moving the pots dot help much, they are allready either turned all the way up or down and it does not help much. I can shrink the image no problem but either top or bottom would be off limits. Colors are good, but i can see like 3 lines on top that do bother me a bit

I found a couple of topics about k4900 monitors but they are not much of help.
Thanks in advance for any help.

 

[nem]

Looks like it's folding over. Replace the caps.

 

[abispac]

To revive this thread since it's one of the first results when you google this issue...

I've had a WG4900 in my Robotron for years, with the same chassis as pictured in the images in this thread, that exhibited the same issue also pictured in the thread. So, as you typically do with monitors, you recap them when there are issues like this. I did this about 5 years ago, and installing the cap kit didn't help at all.

Today I decided to finally tackle this problem.

Looking through my filing cabinet, I found two separate cap kit instructions for WG4900; one from Zanen, and one from some unknown source, but both list C308 as 2.2uf / 50V capacitors.

However, digging through my WG4900 schematics, I found one version of the schematics where C308 is listed as a 3.3uf / 50V capacitor instead.

Willing to try anything at this point, I swapped in a 3.3uf / 50V at C308 and the picture is now perfect! No lines wrapping over at all, and picture fills full screen.

So, there you go; if you just recapped your WG4900 with a capkit and you have vertical fold over, you may have a chassis that requires a 3.3uf /50V at C308 instead.

Found this on an old topic from the arcade museum, im a try this today.

Looks like it's folding over. Replace the caps.