|
|
Pre-show testing found the game working almost perfectly but for some corrupted object graphics on the vault screen. The game PCB was removed for bench testing & repair.
|
Since the bad object graphics was only present on the vault screen I started looking at the object ROMS. Removing IC G19 (masked ROM) only impacted the vault graphics but the defect still appeared to be present. Removing IC J19 also only impacted the vault graphics but the defect was no longer present. Firing up the DataIO to read ROM J19 confirmed that ROM J19 didn't read consistently. Looking at the read data pattern showed some mismatching blocks of data. I programmed an Intel 27128-3 EPROM to replace J19 and that fixed the vault object graphics.
|
Though the soldered lithium coin cells in the Konami games typically haven't leaked as badly as other battery types I decided to remove it anyway as a precaution.
|
Suprisingly the game didn't boot after installation back into the cabinet. I checked the power supply voltages and found them all OK. The board was removed again and returned to the bench for further testing.
|
Alas I didn't have support for the Konami-1 CPU in my Arduino ICT yet and there wasn't time to add it before the show. I remembered seeing on the UKVAC forum that someone had created a test ROM for this platform. I found the ROM from "shoestring" online and doubled the 2764 image to fit in the 27128 configuration of this PCB. The test came up ok, passing all the RAM but giving inconsistent readings for the G5/G7 ROM. To confirm the ROM decoding I swapped ROM G7 with G11 and the test identified all the ROMs correctly, suggesting that all the ROMs were good. Swapping G7 & G11 back into the correct positions found the test still passing OK and I suspected a poor contact on the G7 ROM socket. The socket looked fine (no obvious corrosion), but I cleaned both the ROM and socket pins with a wire brush to be sure. The game booted & ran OK on the bench for several hours and didn't have issues with flexing or pressing on any of the socketed IC's so I declared it good.
|
This time back in the cabinet the game ran OK for several hours with no further issues.