Posts: 1,792
Threads: 62
Joined: Jan 2005
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
Posts: 1,841
Threads: 54
Joined: Jul 2005
Hi,
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.
Raymond
Posts: 145
Threads: 40
Joined: Oct 2005
Hi:
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
Posts: 174
Threads: 32
Joined: Apr 2006
I could not perform a machine reset and the squeeling persists.