Konami Track & Field arcade pcb repair
Booted up to a screen full of 0′s. That meant the CPU was partially running as it was clearing the text layer to consistent 0 instead of leaving it as random garbage. The program ROMs were tested on PC and 2 of the 5 gave inconsistent reads. 2 replacement eproms were burned and game started up!
There was a further graphics problem – corrupt text on the hi-score names in game. At first I thought this might be a problem with the graphics ROMs and indeed 1 gave inconsistent reads, but replacing this didn’t fix the problem. Some Googling revealed this is a common problem when the battery on the board dies – it seems the game then reads garbage data from the save memory and doesn’t do any validity checking on it – so it just copies garbage chars to the screen. A fresh battery was installed and the save memory reset via the dip switches.