HP Forum Archive 07

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HP-34C Message #1 Posted by Fred on 8 Mar 2002, 6:32 p.m. Need replacement battery pack, anyone know where I might find one? HP Part#1403-0313

Easy to make Message #2 Posted by Mike on 8 Mar 2002, 7:11 p.m., in response to message #1 by Fred These are very easy to make. Basically two NiCads or NiMH AA cells will work. You just need to put a piece of metal across the back to connect the non-contact sides of the batteries.

Re: Easy to make Message #3 Posted by Fred on 8 Mar 2002, 8:26 p.m., in response to message #2 by Mike What about polarity?

Photo of 37E Message #4 Posted by Mike on 8 Mar 2002, 9:13 p.m., in response to message #3 by Fred

Re: Photo of 37E Message #5 Posted by Matthias Wehrli on 9 Mar 2002, 4:35 p.m., in response to message #4 by Mike You better use "flat top" batteries.. They do not have the knob on the "+" and so they are 1mm smaller than normal NiCL. If you this parts, you will not break the selsible battery holders in your Spice ;)

Good point. Message #6 Posted by Mike on 9 Mar 2002, 9:56 p.m., in response to message #5 by Matthias Wehrli Good point. They do go in rather tight. I had to use a very thin piece of metalic contact on the right (in the photo) to give it a bit more room. If you don't mind using Radio Shack batteries, you can get them already connected on the right (as shown in the photo). These are the shorter ones that are recommended above.

Re: Photo of 37E Message #7 Posted by David Smith on 9 Mar 2002, 6:23 p.m., in response to message #4 by Mike Before you install a Spice battery pack, place a ribbon or paper around the pack that you can use as an extraction device. I wrap mine with a piece of plastic tape, stuck together at the top to form a tab. Makes removing the pack very easy and no risk of damaging the contacts.

Re: Photo of 37E Message #8 Posted by Bob Senzer on 10 Mar 2002, 11:24 p.m., in response to message #7 by David Smith Hi, I've got an old HP-34C in which the battery compartment and/or battery is quite corroded with all of that powder from the decaying batteries. Is there any hope left for the calc? If there is ... how do I go about removing the metal cover on top of the batteries, i.e. , the one that has the + and - markings on it. I am afraid of doing more damage. On the other hand, the calc is obviously dead at the moment. I notice in the picture of the 37E, the metal cover has been removed. It should be noted that the powder may have congealed everything together already. The metal cover does not yield very well to the regular assortment of fine precision instruments that I have available such as tweezers, paper clips, butter knives, those flat plastic gizmos that keep plastic bags with bread loaves sealed, etc. Thank you.

cleaning corrosion Message #9 Posted by Ellis Easley on 11 Mar 2002, 1:45 p.m., in response to message #8 by Bob Senzer I've never owned a real spice battery even though I have several 34C's. But in general for cleaning battery corrosion I use distilled vinegar diluted 1:1 with water. Then after the corrosion is gone, I rinse with lots of water, then finally with two changes of distilled water. I disassemble things as much as possible and certain things, like transformers that aren't sealed, I don't soak at all. I've had no trouble with soaking Woodstock circuit boards without the LED and Keyboard PCBs, although I once salvaged a badly corroded Woodstock keyboard this way; even though I accidentally poked a hole in a keyboard spring dome while clearing corrosion out of a PCB via with a dental probe, the switch still works. If you don't want to disassemble the calculator, remove as much corrosion as you can with a brush and pick, then swab out with a Q-tip moistened with distilled water: plunge the Q-tip in the water and then "snap" as much water as you can out of it. You can also use a little diluted vinegar this way, but then swab several times with fresh Q-tips and water. There is an excellent article on corrosion on Viktor Toth's Programmable Calculators website (rskey.org).

Re: Photo of 37E Message #10 Posted by Fred on 13 Mar 2002, 10:45 a.m., in response to message #9 by Ellis Easley Thanks Mike, I had some Ni-cad batteries from an old cordless phone after knowing the polarity; they took a charge will be geting the radio shack brand for a permanent pack. Good tip David, Thanks 34C is working great now and holding a good charge. Do you'll know where I can get a listing of the application books that are available for 34C calc.

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