Symptoms: Board would not boot.
Repair:
1.Replaced 1 Z40A CPU that was missing from socket on cpu board.Turned game on and garbage on screen.
2.Verified all Eproms were good, but 7A on CPU board was bad and 5N on Video board was bad. Erased and reburned new images. Turned game back on and still garbage on screen.
3.Tested all ram on CPU and Video board and found Bad ram on CPU board at 7H. Desoldered bad ram and soldered in a socket and added 1 new 2016 ram.Turned game on and game now plays perfect even though I can only get to the third screen as I suck.
On a side note I also tested all the ICs using a BK precision bugtrap and a logic probe and tested the caps for esr values and verifed all the transistors were working too.
Hope this repair log helps you.
Repair:
1.Replaced 1 Z40A CPU that was missing from socket on cpu board.Turned game on and garbage on screen.
2.Verified all Eproms were good, but 7A on CPU board was bad and 5N on Video board was bad. Erased and reburned new images. Turned game back on and still garbage on screen.
3.Tested all ram on CPU and Video board and found Bad ram on CPU board at 7H. Desoldered bad ram and soldered in a socket and added 1 new 2016 ram.Turned game on and game now plays perfect even though I can only get to the third screen as I suck.
On a side note I also tested all the ICs using a BK precision bugtrap and a logic probe and tested the caps for esr values and verifed all the transistors were working too.
Hope this repair log helps you.
