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My Auto Power On HP-32S
09-19-2018, 11:15 PM
Post: #1
My Auto Power On HP-32S
Recently I spotted an HP-32S on TAS, with scratched display frame and in not working condition. I felt sorry for the poor calculator and got it for a very reasonable price.
After replacing the foam under the conductive foil it came back to life. Everything fine again? Well, almost. The HP-32S has an auto power off feature. After 10 min it turns itself off to conserve battery power. Beyond that, mine has a very special auto power on feature: after several minutes it automatically turns itself on and puts a zero into the x-register.
Never seen that before. Any ideas?
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09-20-2018, 12:28 AM
Post: #2
RE: My Auto Power On HP-32S
(09-19-2018 11:15 PM)Pjwum Wrote:  Recently I spotted an HP-32S on TAS, with scratched display frame and in not working condition. I felt sorry for the poor calculator and got it for a very reasonable price.
After replacing the foam under the conductive foil it came back to life. Everything fine again? Well, almost. The HP-32S has an auto power off feature. After 10 min it turns itself off to conserve battery power. Beyond that, mine has a very special auto power on feature: after several minutes it automatically turns itself on and puts a zero into the x-register.
Never seen that before. Any ideas?
Are the batteries fresh?
When this occurs, does it also clear the program memory and storage registers?
Can you measure the battery voltage while it is on and operating?
Does it do this if you turn it off manually?
Does it to this after a while if you keep the calculator on by pressing a key every few minutes?
Do *all* of the keys function?

If everything is being cleared it almost sounds like it is doing a factory reset or power is not being supplied to the calculator while it is off.
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09-20-2018, 10:19 AM
Post: #3
RE: My Auto Power On HP-32S
Quote:When this occurs, does it also clear the program memory and storage registers?

Thank you, Steve! Your questions brought me to the solution. No, it doesn't clear the memory. Just powers on and puts a zero on the stack. Battery power is ok and all keys function. In fact, the intervals between spontaneous power on got larger and the feature vanished after applying my wife's hairdryer.
Some moisture from cleaning the keyboard must have caused a shortage on the conductive foil.
I rather should have cleaned with some alcohol.

Patrick
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