Status: Repaired Successfully on 2/14/2023
In for repair is a Sega System 16B with the Multi ROM board created by Apocalypse.
The main PCB was a Tetris board originally, and the board is clean and in good condition. However, it booted up to Altered Beast with severe graphical corruption and no sound.
First, I physically examined the board and noticed that one of the pins on the 68000 Main CPU was bent out of the socket.
Straightening that pin didn’t fix the issue. I also confirmed that all of the EPROMs on the Multi PCB were firmly seated and that there weren’t any bent or missing pins in between the main PCB and the Multi PCB.
I moved on to pulling each EPROM on the Multi and verifying each chip’s contents. This Multi uses fourteen 27C322 EPROMs and one 27C801. The 27C322’s are notorious for going bad and not taking a new flash – I’ve had around a 15% failure rate with them.
Sure enough, five of the EPROMs ended up being bad and wouldn’t reflash.
After flashing and installing fresh EPROMs for the failed ones, now the game booted up with clean graphics, but there still wasn’t any sound.
It turned out that I had missed another bent pin – Pin 40 on the Zilog Z0840006PSC Z80 Sound CPU was bent inward in such a way that it looked connected from the outside but wasn’t actually making contact to the socket. Straightening the pin and reinstalling the CPU into the socket fixed the audio.