Zinfer
Well-known member
Just punking around on this Red Baron board. Seems pin 40 on the CPU (6502) is blinking high and low. I traced this back by the drawing sets to L10 pin 8. However Pin 8 is high. This confuses me. I thought the signal from L10 Pin 8 ran directly to the CPU.
I also checked Pin 11 and that was blinking high and low. Traced that to M4 Pin 8 which is high.
At first glance I'd have said the problem is at L10 but it threw me when Pin 8 was high but pin 40 on the CPU was blinking high/low.
I exchanged and tested the 6502A CPU with a working Battlezone so I know the CPU is good.
I know that the dogs are barking, but where exactly do you start with a logic probe to find the source? Or is that even possible?
Any ideas?
I also checked Pin 11 and that was blinking high and low. Traced that to M4 Pin 8 which is high.
At first glance I'd have said the problem is at L10 but it threw me when Pin 8 was high but pin 40 on the CPU was blinking high/low.
I exchanged and tested the 6502A CPU with a working Battlezone so I know the CPU is good.
I know that the dogs are barking, but where exactly do you start with a logic probe to find the source? Or is that even possible?
Any ideas?