ShootTheCore
Legendary
I have a Konami Aliens PCB that works fine, except that none of the sound samples will play (like the machine gun sound effects).
@caius documented a repair he made on an Aliens PCB with the same problem, here:
http://www.jammarcade.net/aliens-repair-log/
Unfortunately, his solution of replacing the mask ROM with a 27C400 with the data doubled didn't work for me. I tried both with the ROM data written to the chip directly, and with the data doubled just to be sure. The written EPROM passes verification correctly on the chip programmer.
The Konami 007232 PCM controller is showing activity on the CPU lines, it has power, and it's getting a clock signal, but the ROM address and data lines are stuck low with no activity (the ROM lines were all stuck high on @'caius''s board). ROM pins 14,16,18,20,23,25,27 all read as floating on my logic probe, but the schematics show that those lines are unused.
I've also tried pulling the reset line low a couple of times on the 007232 in case the controller had crashed, but that made no difference either.
At this point, I'm thinking the 007232 custom itself has failed, but I want to get a second opinion before going through all the trouble to find another one and performing the soldering work to replace it (64 pins!).
Any ideas?
@caius documented a repair he made on an Aliens PCB with the same problem, here:
http://www.jammarcade.net/aliens-repair-log/
Unfortunately, his solution of replacing the mask ROM with a 27C400 with the data doubled didn't work for me. I tried both with the ROM data written to the chip directly, and with the data doubled just to be sure. The written EPROM passes verification correctly on the chip programmer.
The Konami 007232 PCM controller is showing activity on the CPU lines, it has power, and it's getting a clock signal, but the ROM address and data lines are stuck low with no activity (the ROM lines were all stuck high on @'caius''s board). ROM pins 14,16,18,20,23,25,27 all read as floating on my logic probe, but the schematics show that those lines are unused.
I've also tried pulling the reset line low a couple of times on the 007232 in case the controller had crashed, but that made no difference either.
At this point, I'm thinking the 007232 custom itself has failed, but I want to get a second opinion before going through all the trouble to find another one and performing the soldering work to replace it (64 pins!).
Any ideas?