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HP-21 repair
10-15-2021, 07:17 PM
Post: #1
HP-21 repair
I have a HP-21 that turns on but only displays a zero on the right of the display, an occasionally 3 zeros across the display. The keyboard is unresponsive. Is that a clear sign the ACT chip is dead or could the problem be caused by something else, such as cross talk between PCB traces, or a defective discrete?
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Messages In This Thread
HP-21 repair - Benoit Maag - 10-15-2021 07:17 PM
RE: HP-21 repair - rprosperi - 10-15-2021, 09:30 PM
RE: HP-21 repair - teenix - 10-15-2021, 10:56 PM
RE: HP-21 repair - Benoit Maag - 10-16-2021, 12:46 AM
RE: HP-21 repair - rprosperi - 10-16-2021, 01:14 AM
RE: HP-21 repair - Benoit Maag - 11-16-2021, 08:12 AM
RE: HP-21 repair - rprosperi - 11-16-2021, 01:55 PM



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