xodaraP
Legendary
Bought a Tumblepop recently with no sound - decided to have a look at it and see if I couldn't get it going. I pulled off the 2 sound ROMs (1 for sound fx/music, one for voice effects through the Oki sound processor) and found 2 issues. The 27C512 for the main sound FX and music was completely dead, so I replaced it, and the Oki CPU had a 27C010/1001 EPROM installed, but the board was silkscreened for a 27C1000 - so I replaced it with a 27C1000.
Still had nothing, so checked the usual stuff (power, clock, reset) on the sound CPU and found that clock was missing. Traced this back to a 32mhz crystal which was working, but not getting to the sound CPU. Found if I applied pressure to the crystal, clock signal would return to the CPU. I resoldered the crystal in place and I now had clock. The board now had sound effects and music!
Looking at a video of a playthrough I realized I was still missing voice effects. I decided to put the 27C1001 compatible EPROM on the board that came with it, as it was entirely possible the jumpers on the board had been reset to support a different style of EPROM at the factory. This restored the voice effects and gave me a 100% working board!
Still had nothing, so checked the usual stuff (power, clock, reset) on the sound CPU and found that clock was missing. Traced this back to a 32mhz crystal which was working, but not getting to the sound CPU. Found if I applied pressure to the crystal, clock signal would return to the CPU. I resoldered the crystal in place and I now had clock. The board now had sound effects and music!
Looking at a video of a playthrough I realized I was still missing voice effects. I decided to put the 27C1001 compatible EPROM on the board that came with it, as it was entirely possible the jumpers on the board had been reset to support a different style of EPROM at the factory. This restored the voice effects and gave me a 100% working board!
