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HP 25 Flaky Power Switch - Printable Version

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HP 25 Flaky Power Switch - oldRPNlover - 08-10-2020 09:34 PM

I have an HP25 which served me well back on college (a long time ago). It is in good condition with no corrosion on battery tabs. I replaced the batteries out of caution since the ones in there were from 2005. It appears as though the power switch is flaky because it comes up with various digits (0s) upon start up. Usually the first two digits light correctly. Sometimes I get all the LEDS on (0s), and sometimes a few zeros and some decimals, and just about any combination imaginable. If I wiggle the switch, the display changes.

The batteries are charged well and seemingly making good contact.

I have it apart but see no way to clean that switch and the keyboard does not come apart. I hate to spray anything but air in there.

Thanks for any insight!

RE: HP 25 Flaky Power Switch - mfleming - 08-11-2020 12:41 AM

A drop of DeoxIT Red (D100) contact cleaner on either side of the switch followed by moving the switch back and forth to work the cleaner in and remove the buildup helps. See this URL for the various forms available.


I assume the calculator does turn on correctly if you can find the right clean spot on the switch. Otherwise the problem may be more serious...

RE: HP 25 Flaky Power Switch - oldRPNlover - 08-15-2020 09:33 PM

Thank you mfleming! That did the trick - much appreciate your suggestion!