Spice battery contact board



#7

Is it possible to get this board replaced? I got a 34C from someone and it's corroded bad enough that it's lost the contacts. It looks like new pieces of metal could be soldered on maybe, but since from the outside, it looks like a separate board, it would be nice if I could replace it. Any ideas or sources?

Also, on the batteries. I did a search on here, and saw people talking about just using two AA NiMH batteries, which sounds like the way to go. Do you tape or shrink them together, or just use them separate. The latter would make them easier to charge, but I was just curious if it would work.


#8

I can't help you with your question on repairing the corrosion. Fortunately, in my 33C and 34C the contact board is still in good shape.

I use AA NiMHs. I complete the circuit on one end with a bit of aluminum foil taped in place, and tape the cells together with a bit of packing tape. I then gently ease the exposed end of the new "pack" into the calculator up against the connectors (remember the positive end is bottom, negative top), and gently ease the other end into the battery compartment--since the positive end buttons on the batteries add some length compared to the original Spice pack, the fit is snug. The risk of this is that the contacts can bend in too far and break. Indeed that is the case with my 33C--the positive connector is gone, but enough of a stub is present to make adequate connection with the battery, but if I ever wish to resell the calculator purist collectors may object.

Due to the snug fit getting the pack out requires care--I just gently rap the calc on my palm so the end slips out a bit, then gently ease it out from there with thumb or finger. It is easier and safer to remove from the end away from the contacts, just as that end should be the last to go in when you put the pack in.

If you have the original metal sleeve from an original Spice pack, that is a bonus, since I am sure it makes a better and more reliable completion of the circuit than my tape and foil arrangement. Also, you can always just slip the cells out of the sleeve and charge them in a proper NiMH charger, since I suspect the Spice adapter probably takes a long time for a full charge. That said, after a few hours of charge in the calculator I fine that one of my makeshift NiMH packs will chug along for 18-24 hours at least in an endless loop program running at FIX 9. That is more than adequate for routine use.

The big objection to the use of standard size AAs in a Spice calculator is the potential breakage of the contacts due to a snug fit. I think if they are available it may actually be wiser to get NiMHs that have the recessed nipple at the positive poles. Indeed, if I can find such a beast I gather that is what I should use.

In the alternative, if you don't completely loathe NiCads, you can get one of waterhosko's Classic packs, disassemble it, and just use two of the cells. Indeed, I suspect if you are careful you can preserve the desired positive to negative connection between a pair and therefore not have to deal with a bit of foil or metal to complete the circuit.

Hope this helps.

Les


#9

I guess since I raise the issue this would be a good place to ask:

Anyone know the current rating of the Spice adapter? I am sure it is not as potent as an NiMH quick charger, but it would be nice to know that it is a little better than a slow trickle offered by NiCad chargers.

That said, I take comfort in the knowledge that if I lessen the lifespan of my Spice NiMHs by repeated partial charging and discharge, at least the cells are readily available and inexpensive--I have seen four-packs of 2600mAh Duracells for $20 here, and they are probably cheaper in the US. For this reason, I have no trouble keeping my 34C charging much of the time, like my electric toothbrush or razor. I wouldn't be quite so cavalier with my Classic NiCads or my waterhosko pack in the 82143 printer--those packs are tougher to get, need to ordered and shipped, and are correspondingly more expensive.

Les

Edited: 11 Feb 2007, 5:37 a.m.

#10

Ruben --

I do something similar to Les' method for my HP-34C with broken contacts but good traces -- 2 AA NiMH cells with a folded aluminum-foil jumper. I don't tape them together, as they are held in place very tightly.

I've never seen NiMH cells that did not have a post on the positive ("+") terminal, which disposable alkaline AA cells also have.

Katie Wasserman prepared instructions on fabricating new battery contacts:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv007.cgi?read=14438

If your HP-34C is pre-1982 or perhaps even early 1982, it is of the original design in which some components are pressed together instead of soldered. These units are heavier than later ones, due to a metal backing plate. It was a bad design; the older units tend to malfunction due to poor electrical contacts.

Year of manufacture = first two digits of serial number + 1960. Example: 2134A12345 = 1981.


-- KS

Edited: 11 Feb 2007, 4:03 a.m.


#11

Quote:
I've never seen NiMH cells that did not have a post on the positive ("+") terminal, which disposable alkaline AA cells also have.

Sorry, I wasn't referring to the cells themselves--of course the positive end is marked!

I am referring to the contacts inside the battery compartment. They are not marked and I have erased my memory on a couple of occasions by putting the pack in backwards!

What I meant was that the positive CONTACT is the bottom one.

I have a 1980 34C, but it feels much lighter in the hand than my 1980 33C. That said, if it has the poor pre-1982 design I will have to be careful with it.

Les


#12

Quote:

I have a 1980 34C, but it feels much lighter in the hand than my 1980 33C. That said, if it has the poor pre-1982 design I will have to be careful with it.

Les,

don't worry. The poorer design is the heavier one, as it has a thick stamped sheet metal piece inside to make the press-together-wiring work (at least for the warranty period of six months, sigh). Those were calcs were cheap and apparently not built to last forever. The laster Spices using traditional soldered PCBs are lighter and last for a long time. I still use my soldered 32E I bought in the early 1980s.

Regards,
Bernhard


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