41c with 785 registers?

[Pieru]

Thanks for the answer.

I previously cleaned contacts, flexibles pcb, looking for corrosion. (I’m engineer in electronics).
Nothing. Contacts are good.
I swapped the board with an hp-41cx (my one). Without problem in the cv case.
Same problem with the cx case, the cv board behaves misfunctioning.

I’ve unsoldered the + pin from the backup capacitor. No more success after resoldering it.

Seems to be bricked ?
Unfortunately, it’s not easy to check the board when in case, with keyboard and batteries...