Unfortunately, using a logic probe is an art and not a science. Some people like to start at the CPU and work their way out looking for bad chips. Other people start at the clock circuit. And some people just start at random.
For me, I usually start at the reset line on the CPU, at least for the Williams boards. If you get the watchdog to trip, then at least you know the clock and a part of the circuit is working.
I tend to print one of the component maps and a closeup of the section of the schematic I want to look and and then make notes about what I find. If I see something strange, I will hook up a working board and see if I see the same behavior.
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