Mine doesn't do this at all...can't make it either....I max out the coins, then use one or two, then power off(let sit a few minutes), power on, credits are still gone. I do not get any errors returned from test...anyhoo, tried to recreate the problem and couldn't...so perhaps that error has something to do with it?
That error for IC29 is caused by a memory cap leakage that leads to corrosion. I just had a board fixed for this. You are lucky to get a game at all :smt020 all I got was ERROR (I can't remember the number but I think it was 02) this game is not acceptable by mainboard. :smt020