Bally Nitro Ground Shaker (Bally, 1980) Bally -35 MPU continuously flashing

[hawkeye]

I'm trying to revive my Nitro Groundshaker. On power up I get the flicker and then the LED continues to flash, it wont stop. Never seen this before. Anyone have any suggestions for a starting point in troubleshooting.

 

[spalmer]

Check to make sure you don't have any battery acid damage on the board.

Other things that can cause this issue....

This can happen from a bad 6810 RAM at U7,
or possibly a bad socket or broken trace at U7. Also there can be a broken trace or
bad socket at the U11 PIA especially around pins 35 to 40. Since U7 and U11 are in
the "battery corrosion zone", look for broken/corroded traces or bad chip sockets in
this area. If there is still no seventh flash, the last thing to check is U14, after the
7th flash, the bally mpu enables the IRQ line, if the IRQ line is broken, the MPU will
restart over and over. In particular look at resistor R134 (4.7k), if this is out of spec​

it will cause the board to boot over and over.