HP-65 1333A18516 - [SOLVED] request for advice

[albertofenini]

(06-15-2024 01:00 AM)teenix Wrote:  If you can use your oscilloscope, you can check the signals going to the anode/cathode drivers.

Page 10 of my Classic Notes

If they are ok, then probably one of those IC's is faulty. If that area of the board has been reworked, maybe damage occurred. If you have spares, then swapping one IC at a time might reveal the problem.

cheers

Tony

Thanks for the advice Tony, we will certainly try but all the IC have already been replaced
with working ones from a donor, that's why we believe that the culprit has to be in the pcb,
problem is in which trace or in which area and how to find it

Where and what exactly should we measure ?

The reworked area has been cleaned and clearly inspected and looks ok so far ...

Thank you so much !