HP-41CX

[Captainsimos]

I am new here so please be patient. I purchased a HP-41CX that doesn't work. The battery terminals are corroded and that is probably the problem. I also have a 82059D charger that is suppose to be for this unit, but I can't figure out where it plugs in. There is an opening on the right side, but no prongs. Am I missing something. Thanks for any help and a great site.

[David Hayden]

There was a rechargable battery pack available. The prongs for the pack lined up with the hole that you see. Without the rechargable pack, you'll need to clear the contacts and get some N sized batteries.

[Captainsimos]

Thanks for the information. I tried cleaning the contacts and installing new batteries, but nothing.

[db (martinez, ca.)]

Three free things to try:
Make sure that you have the batteries facing correctly.
Try squeezing the front and back of the case together in various places while pushing the on switch. Having two left thumbs helps here.
Some switches prefer to be stroked while riding a bit toward the screen or away from it. Don't use a lot of force doing this, just try a few differing motions.

If those don't work, clean your contacts again and see if you have any places where you see missing copper so it is just bare plastic. There are metallic paints available at places like radio shack. This will be a tiny can with a tinier brush of metal fines (mine is nickel) that you can apply to the areas of your battery contacts that have flaked off. If this fixes it, remember that this is only a temporary fix and you will need to repaint it each time you change batteries. The corrosion could have also gone up where you can't see it and have destroyed the fine traces higher in the ribbon. A man in the Canary Islands has made replacement batt contact/ROM contact assemblies. You can buy one of these and it is an easy job to put one in, but that comes later.

There are about 15 or so more things to try, but with your unit's problems you might start with these.

[Håkan Thörngren]

Make sure to get 1.5V N size batteries, not 12V which will fry your HP-41.

[Martin Pinckney]

All N's are 1.5v. It is the 12v A23 to avoid, which is almost the same dimensions.

[Garth Wilson]

fixthatcalc.com seems to have an outstanding reputation for fixing these.

I wouldn't worry about rechargeable batteries unless you're making heavy use of the optical wand or the card reader. Without those, a set of alkaline batteries will last a couple of years.

[John Robinson]

Is it a fullnut or halfnut ?

Cheers,
John

Edited: 26 Oct 2010, 7:32 a.m.