HP-41C high freq. beep


I ahve a couple of HP-41CV calculators tghat just emit a high frequency beep when they are turned on. Does anybody know what might be the problem?


Are these fullnut (1979-1984) or halfnut (1985-1990) units?
(Check out this website for details.)

I bought a fullnut 41CX that displayed gibberish and emitted a high-pitched tone, punctuated by pulses at-one-second intervals. (The CX clock might have explained the pulses.)

An ultrasonic cleaning and resoldering of bad contacts by www.fixthatcalc.com fixed the problems.

NOTE: Fullnuts are more servicable and repairable than halfnuts.

-- KS



this usually occurs when the tone register hasn't benn resetted properly,

which can be the case after a lockup or after inserting batteries

Perform a BEEP (press SHIFT 4) and the HF tone will go away.




A full reset should solve that problem.
Schitch off the calculator. Press "del" (keep it preseed)and then "on/off". Release "on/off" and finally release "del". If you read MEMORY LOST the reset is done.

Good luck


I could not perform a machine reset and the squeeling persists.



Remove the battery pack and short the end battery terminals together (just for a moment). Install batteries again. May be you have to press the ON key more than once to turn the calculator on. If it doesn´t work you need it to be internally cleaned.



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