The Museum of HP Calculators

HP Forum Archive 18

[ Return to Index | Top of Index ]

hp 25 calculator
Message #1 Posted by Tom Harding on 15 Dec 2008, 10:35 a.m.

I inherited my dad's hp-25 and after getting new batteries it works except for the 4 key. Any ideas? I would also like the charger and cord. Tom

Re: hp 25 calculator
Message #2 Posted by Hal Bitton in Boise on 15 Dec 2008, 11:55 a.m.,
in response to message #1 by Tom Harding

Hi Tom,
My 29C has a balky 2 key, and I find that putting a bit of downward lateral pressure on it while pressing makes it work. You might try that with yours. Unfortunately, accessing the keyboard contacts is difficult, as that assembly is heat staked together on the Woodstock series machines (which includes the 22, 25, 25C, 27, 29C). Randy Sloyer at may be able to do something with it, but in looking at his website just now I see that he is not accepting units for repair until into January of next year.

Concerning the charger...I would strongly advise that you never connect the charger to your HP25. There was a dubious design element in the Woodstocks, where the battery pack served as the voltage regulator for the charger. Therefor, if the battery pack ever develops an electrical open (bad contact, corrosion, bad battery, etc.) while the charger is connected, an over-voltage is applied to the calculator, which more often than not results in it's untimely demise.
I use NiMH batteries in my 29C, which I charge in an external charger. If you cut the center beam out of the calculator's battery pack, getting the cells in and out is easy. Good luck with your 25, and let us know how it goes.
Best regards, Hal

[ Return to Index | Top of Index ]

Go back to the main exhibit hall