HP-10 disassembly/reassembly

[[kby]]

I was alluding to an electrical fault on the PCB between the keyboard and CPU pin. It is possible that if all 8's were displayed that the corresponding digit might look slightly dimmer or brighter - hard to say.

A scope attached would at least verify that the correct signal is present. Hopefully not, but you might well see the correct signals getting to the CPU pin, but the CPU may not be interpreting it properly. Maybe the K12 line is driving the display but not LO enough to be detected as a key press. All just guesses of course :-)

The display on HP calcs flickers off briefly while the key press is processed by the CPU. Does this happen on the HP-10, and also the keys in question?

cheers

Tony
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Haven't quite gotten desperate to hang the scope off of it (reassembly of the case is problematic as noted above) and not quite ready to do that for what would seem at best very interesting but not that helpful information.

The display does flicker on other key entries but not the bad keys. The flicker is much briefer than other calculators.

I would say the overall display seems a little on the dim side relative to other machines, but not enough that I could tag it as unusual.

all "8"s look pretty uniform.-kby