HP35 problem with a calculator, maybe due to a faulty charger

[aurelio]

(03-21-2021 01:44 AM)teenix Wrote:  Maybe just pure chance the calculator is playing up this time.

With luck, it may be just a loose or dirty connector between the keyboard and CPU board upsetting the data sent to the anode driver or the CPU clock signal.

cheers

Tony

Hi Tony, I've cleaned with isopropilic alcohol the connection between keyboard and CPU board, but the result does not change. I've to say, just to share, that the response on the calculator changes regularly, depending on the key pressed, for example if I key the 1/x or SQR or Ex I have each time different a recurrent results for each key, but if I press any of the numeric key the calculator turns off. I checked the circuit with a magnifier and the components and the solderings look externally all good