I got this machine broken. It powers up to a green screen and the ROM board reports 1-3-1. If I reset, it just repeats the 1-3-1.
It started with a blown BR1 on the power board which was taking out fuse 4. That's now fixed.
From my studies, I measured voltages on the RAM chips (per the manual) and all the voltages are very close:
Pin 1 -4.94
Pin 8 12.15
Pin 9 4.96
All three leds on the powerboard are on when 4J2 is connected or disconnected. The bottom one does seem a little dimmer.
If I hit the button on the sound board, it repeats what I think is the flapping sound.
I found in another thread that a guy fixed a similar problem by replacing 7410 @ 6I. How can I further isolate the problem. I don't have a logic probe, but if that's what I need, I'll get one.
What should I do?
It started with a blown BR1 on the power board which was taking out fuse 4. That's now fixed.
From my studies, I measured voltages on the RAM chips (per the manual) and all the voltages are very close:
Pin 1 -4.94
Pin 8 12.15
Pin 9 4.96
All three leds on the powerboard are on when 4J2 is connected or disconnected. The bottom one does seem a little dimmer.
If I hit the button on the sound board, it repeats what I think is the flapping sound.
I found in another thread that a guy fixed a similar problem by replacing 7410 @ 6I. How can I further isolate the problem. I don't have a logic probe, but if that's what I need, I'll get one.
What should I do?
