Christian,
Thank you for the reply.
I just rechecked the STROBE (Digit Select) signals on pins 26-28. All three signals are always HIGH (+5v). The only time that they change is when I plug or unplug the receiver.
I’ve checked these in the past and expected to see them changing. My assumption is that all HIGH on these signals means that the display is either meant to be blank or that the CPU is not properly updating the signals. Since some of the other signals that I expect to change during power-up are not changing, like the RELAY signal, my theory is that the CPU isn’t running properly.
I think that the STROBE signals and the downstream circuitry is not broken since I was able to get the “P” display, as well as other LEDs randomly lit, when I ran the microprocessor board outside of the chassis with bench power supplies.
My interpretation of what I’m observing is that the CPU initially starts, then fails or stops at random times. What I see on the displays and other signals depends on how long the CPU runs before it has an issue. Of course, I might be having tunnel vision on this theory and would be happy to try alternative solutions.
What did you do to fix your STROBE issue on your BM8000?
Glitch
