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

[aurelio]

(03-20-2021 02:11 PM)Maximilian Hohmann Wrote:  Hello1

(03-20-2021 01:45 PM)aurelio Wrote:  The calculator turns on (with a charge battery pack), but shows erratic behavior by showing meaningless numbers on the display. any idea what might have been damaged

Before trying anything else I would connect a laboratory power supply set at something between 3.6 and 4 volts to the battery contacts directly (carefully watching the polarity). If it still behaves strangely you can start troubleshooting. With old battery packs you never know: It could be contact problems or a dying battery cell.

Good luck
Max

Thank-you Max, actually I fed it with different battery pack aleady tested (I mean they work with other calculators) and the result is the same. I read on the forum that "this machine will work just fine without a battery pack installed. The power supply for the classic series machines delivers a filtered and regulated voltage to the electronics and a separate voltage to charge the battery pack". well, feeding the calculator without the battery pack inside using different already tested wall charger the behaviour I get is the same (erratic).

I'm scared that the wrong initial voltage (17V circa) in place of the 4,5 could have damaged the circuit, far away still to understand what, specifically