4 slot MVS - No video at all

[Hackcell]

Just connected a MV4-FT2 I purchased online. The video was like "waving", slowly shaking. When I tried to change from slot 1 to slot 2, it showed me a BANK ERROR message and the system froze. I restarted it and there was no video anymore. Sound works fine, changing games works fine, but there is no video at all. The monitor reports "no video input". I changed to a CPS2 and the video works like a charm.

Any suggestions on what shall I check?

Thanks.

 

[KmanSweden]

Check for corrosion near video ram. Broken traces are common. On This board slot 1 & 3 had no picture or sound. Fixed one broken trace and both slots came back to life.