HP-65 1605A02841 - weird display and card reader issues

[albertofenini]

Hi Everyone,
this an update of an older post, basically this unit has an hybrid pcb and a keyboard/led pcb with this issue :

When used with its own hybrid the display turns on the requested segments for the requested digits PLUS all the decimal points and all the C segments

When used with any other different (known working) hybrid the display turns on the requested segments for the requested digits PLUS the decimal points
and the C segments for the digits actually used plus the one after the last one

I think the pictures will better describe the situation

All of the waveforms have been taken using a known working hybrid logic board

Quite surprising all the waveforms are of the correct form and value

What could it be the problem ?
There are no open coils but we don't know how to test if some coils are shorted together

Unluckily we have not taken the waveform for Anode segment C when it should not be on, like when the display is showing a 2

Thanks in advance for any advice !

Pictures : HP-65 1605A02841 - wrong display behavior