How to repair a Hewlett-Packard HP 32Sii calculator

HP 32S II calculator recovering from surgery.

ure, the H/P 32Sii is not very powerful. It's not the nicest-looking calculator ever made. It's not the fastest any more. But it uses RPN, and it's the most convenient calculator ever made for converting numbers into hexadecimal and back. Online vendors are asking $699.99 for them. So we want to keep our old one running as long as possible.

Unlike the HP-15c, which has screws hidden under the rubber foot pads, the back cover of the HP 32Sii is attached by hidden weld points. This makes it hard to open without chewing it up. I was able to remove corrosion in an HP-15c using a pair of tweezers and a small rag soaked with ethanol, which gave it an extra ten years of life. That's harder in the 32Sii, because it's designed to be disposable.

The problem is that the circuit board loses contact with the keypad. On mine, it got to the point where only the On and the 4 keys still worked. Something had to be done.

Before cutting, try resetting the calculator first. Take the batteries out and use a wire to short the terminal tabs for ten seconds. It will say ‘MEMORY CLEAR’ when you power it up.

If part of the keyboard doesn't function, it's probably a faulty contact. Use a Dremel to cut a rectangular hole in the back at the spot where the recycle logo is, at the level of the √x key. You should see a copper clad circuit board. Stuff some cardboard in the slot to push down on the board until all the keys work. Then glue the plastic back in place. Hold it in place with duct tape until it is healed.

If your HP32sii is corroded, you'll need to remove the whole back cover. Luckily, there's lots of empty space in there, so it's reasonably safe to cut all the way across the back.

Didn't think of that one, didja HP?

jan 18 2015