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Full Version: HP35 HP45 battery charger. Random display values.
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People have posted with the problem before but none of the replies deals with the issue properly. I'm posting this in the hope it goes into the archives and the next searcher finds the solution faster than I did.

The problem is cause by the electrolytic capacitor ( 400uf 15volts) found in the battery charger drying out.

Replace the capacitor and the problem goes away.

Thanks for a great site.

Charles Esson

I have several chargers, does this mean I should make a rota so that they are each used in turn?
Does this only affect Classics chargers?



Thanks for bringing up this topic. I was asking (at multiple places) a question regarding an old C= calc and irregularities when charging it. Thanks to the good people on the usenet, I was able to resurrect it by exchanging the capacitors.


Drying out is the fate of every non-hermetically sealed electrolytic capacitor. Some last 20 years, some 30 years, but their death is inevitable.

My experience with Classics chargers is that if they are used, and the
seal of the electrolytic capacitor is already a bit deteriorated, then the heat produced by the charger will quickly finish them.

Dying electrolytic capacitors can make quite a mess. Best mode to handle this problem is perhaps to exchange them against new ones as a routine precaution, even if the charger still appears to work.

Woodstock chargers contain only a transformer and no electrolytic capacitors.