HP41C power problem

[Steve Budd]

Hi,
I have an HP41C which has worked brilliantly for over 20 years using alkaline batteries (since the rechargeable pack gave up some years ago). A colleague of mine gave me an HP41 battery charger and battery pack which I tried in my own 41C for half an hour, but it didn't work, so I went back to the alkaline set that I had been using before but now the calculator won't power up at all! I hope that using the charger hasn't caused any lasting damage. Is there anything I can try to get it working again? Failing that, is there anybody that can repair an HP41C here in the UK?
Regards,
Steve

[Klaus]

The battery contacts are made of very thin foil. There is a chance that this foil was broken by inserting the rechargable pack. One can solder this, or someone here sells replacement foils.

Please note that a very common problem is internal corrosion or bad contact of the "zebra connector" between the keyboard and the logic board.

[Randy]

Put the soldering iron away...

It is very easy to send a 41 into la-la land by lowering the internal voltages and causing memory corruption. The rechargeable battery could have been shorted such that the 41 would little to no voltage even with the charger connected.

You probably just jumbled its tiny little brain. Try clearing memory and it should recover.

Press and hold the backspace key.

Press and release the ON key.

Release the backspace.

You should see MEMORY LOST.

If that doesn't work, try removing the batteries and reinserting a few times, try the reset after each attempt.

Here are a few more reset techniques

As for the previous post:

Quote:

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Please note that a very common problem is internal corrosion or bad contact of the "zebra connector" between the keyboard and the logic board.

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While this might be correct for units that have suffered a battery leak, that is certainly not the case here. The 41 worked one minute, not the next. Why assume it corrosion? IMO, common sense says otherwise. Besides, what if the unit is a halfnut - what then?

Edited: 30 Jan 2007, 8:47 a.m.

[David Smith]

Actually, it could be something like that. A lot of the rechargeable packs take a bit of force to insert/remove. If you had a marginal contact (or cracked post/boss) this can be enough to push it over the edge. Try squeezing the machine near the battery contacts and the cpu contacts while powering on and see if that helps.

[Steve Budd]

Thanks for all the positive help and suggestions. As soon as I get back I will try them out and hopefully I will have a 41C with a new lease of life.
Thanks again.
Regards,
Steve

[Bram]

I have a battery pack in which batteries 1 and 2 are connected and supply 3 Volts, but batteries 3 and 4 aren't. No damage seen, but anyway easily repaired with a strip of alu foil between the batteries and the springs.

I don't expect you're dealing with a similar case, but I'd check the battery voltages to be sure.

[Ron]

This doesn't apply directly to your problem, but your problem got me to trying a few things on a 41C that I haven't been able to turn on.

I have a CX that has been working fine. I commonly just exchange the battery holders between calculators (exchange the full one in the CX for the empty one in the C, in this case). After inserting the full battery holder in the C, it wouldn't power up. I knew the batteries were good, as they just worked in the CX.

After much frustration, trying all the resets listed above, I decided to check the batteries, even though I knew they were good. As it turns out, two were very weak. Even though they powered the CX, they wouldn't touch the C. I put in new batteries, and the C's now running like a champ! Go figure!

The CX is a half nut. I guess it takes less to crank.