HP15C displays gibberish. Is it broken?

[lyuka]

(10-05-2020 07:46 PM)Marcovecchio Wrote:  or 15 minutes, it started working ok again, and I noticed a big resistor-like component was hot. I think it's not a resistor, but an inductor, used to generate calculator clock.

It was not the axial lead inductor that was hot, but the dip tantalum capacitor at the power input. It is easily broken in short mode by reverse voltage supply. In this case, it miraculously protects the processor. After that, it is presumed that the short-circuited state became open and the operation was restored because the fuse in the tantalum capacitor was blown or the solid tantalum was completely burned down.

Lyuka