Power switch repair


I just picked up a HP-55 and the power switch is not making good contact at the detent or far right position.

Slide it back a bit and it works fine.

Is there any non-intrusive remedy for this?



AFAIK, there is no way to acomplish this without opening the calculator to clean the contacts. The only problem is that you must pull back the top of the large back label to access the two middle mounting screws, and it's quite tricky to do this without damaging the label in the process. If this is the only problem and the switch can be made to work properly, I wouldn't bother with it. The only time I open a classic calculator is if some of the key contacts require cleaning or to effect some other repair.


Unfortunately no non invasive way.

try this link:

HP 45 restoration

Michael is correct, the only way in is to remove the big label. Check out the link and scroll down also as I describe the way to remove the label and then flatten it to restore it to pristine shape.

Cheers, Geoff

Edited: 27 Feb 2010, 1:30 p.m.


I'd like to add that I've followed Geoff's instructions for disassembling an HP-45 with great success. My repairs involved the power switch, keyboard cleaning, and resoldering a couple of broken tracks. The calculator came apart beautifully and is back together once again, as good as new. Smoothing out the label and re-applying it was also successful.

I really enjoyed doing this - thanks, Geoff!


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