The game belonging to my personal collection didn’t boot anymore after several years kept in storage.
Game was in mint condition but the address decoder custom 34 had lot of oxidation on the pins (common problem on these custom chips) so I proceeded to clean and reseat it paying particular attention to avoid breaking pins which generally are really weak.
Game booted but it developed the following problem
After probing around on the rams and TTL for suspicious signals with no luck I decided to dig up my dead Gaplus board which I kept in my garage for Namco customs spare parts and checked one by one each custom.
After changing the CUS20 (tilemap and sprie address generator) the problem was fixed
Another Fujitsu chip left our world.