For Sale HP-41CX + accessories

[MichaelHarwood]

HP-41CX for sale

Accessories:

* original case + foam rubber insert
* HP-41C Manual NOTE: this is NOT 41CX manual. I bought the calculator second hand in the early 2000s and it came with this manual.
* HP-41CX Quick Reference Guide
* Math Pac Module (purchased 2009 on Ebay)
* Math Pac Module manual
* 4 keyboard overlays
* one black holder that holds the overlays and three expansion modules
* Card reader. The card reader was repaired a number of years ago so that the rubber wheel is not gummy any more.
* 25 cards. They are in two separate packages (9 and 16 cards). It seems that I used 9 cards and the 16 cards are blank.

The calculator works fine. However, I have used it less and less over the years and have hardly used it at all since the pandemic. I am now retired and I need to sell it so that someone else can enjoy it.

I believe that the case is not screwed shut (none of them are?), and, alarmingly, it started opening a couple of times at the top. This is the reason that I bought the Math Pac module. Keeping the math module in place fixes this problem.

Sadly, I forgot a set of batteries in my calculator and they corroded. I've tried to clean as much of the corrosion as I can. You can probably do an even better job. The calculator still works.

My biggest issue over the years, the one that drove me completely nuts, was the N size batteries. They're very expensive and they don't last long once the card reader is being used. I tried various ways to fix this.
My first idea was to get a second battery holder, remove the separating plastic and then put in a nice, large, cheap 6V battery (Duracell 7K67 battery). However, I had trouble reliably connecting the +/- of the battery to the calculator.
My second idea was to have an external power supply, and solder wires to the + and - terminals of the battery holder. I did it in such a way that the N batteries would still fit at the same time. Problem: the two 6V power adapters that I tried didn't work. I suspect that they have too much AC ripple on the 6V.
Third idea: instead of an external 6V adapter, get 6V external batteries (e.g. 4 D cells). I never got around to doing this. Using AA would be better -- less bulk.

Anyway, this explains what you see when you look into the battery compartment (see attached photos):

* There's a little corrosion. The -ve terminal looks bad, but a lot of it is solder.
* There's a red and black wire soldered to the +/- ends, and the wire snakes out the port.
* One of the spring tops broke off (due to corrosion?). The rest of the spring is still sufficient to make contact with the N cell.

With appropriate tools, you could remove the solder and extra wires and restore things to how they were.

Card reader:

I purchased 4 N batteries on 22 March 2024 and tried it out, after not using it for perhaps 4 years. There were some "malfunction" messages, which means that the head needs cleaning with a cleaning card. I don't have one.
I tried a few times and was able to get a program card read in as well as my status card (both sides). What happens is that it doesn't always recognize that there is a card in the reader, so you have to wiggle it in and out a bit or else push it in more firmly in. Out of the 8 times I tried to read a card, it worked 50% of the time. I think someone who knows more about this would be able to get it working, or maybe just more use of it would fix the problem. Some cards had check sum errors - which might be the card or the card reader.

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IMAGES: There are four photos. See https://imgur.com/a/mqiCQ5N
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I'm asking US$200 for everything. Since I live in Canada, I imagine that shipping will be about $30 to anywhere in USA and Canada. I'll make sure that it is well packed and has a tracking number.

Please feel free to ask for any more information.