HP-10 disassembly/reassembly

[teenix]

(02-14-2020 05:45 AM)[kby] Wrote:  ......the "5" and "2" keys don't work.

A voltmeter connected to CPU pin (37) and ground while the calculator is running should show a small voltage change when either of those keys are pressed. A better method is using an oscilloscope which you can see either key press as a low going pulse.

Seeing that you appear to have checked the common trace for these 2 keys back to the CPU pin, it would seem to suggest that the CPU chip has failed.

cheers

Tony