The Museum of HP Calculators

HP Forum Archive 08

[ Return to Index | Top of Index ]

42s batteries
Message #1 Posted by a on 26 Mar 2002, 10:24 p.m.

Is there a longer-lasting alternative to the 3x button cells? Mine always seem to die during a period of low use - requiring re-programming... very tedious. My 28s otoh, has been running for YEARS on the same batt! thanks a

      
Re: 42s batteries
Message #2 Posted by Vieira, Luiz C. (Brazil) on 27 Mar 2002, 8:00 a.m.,
in response to message #1 by a

Hi;

I have a 42S that is not so power consuming. It really rests when switched to OFF. I once saw an HP15C that eat batteries: no more than one week for fresh alkalines, switched ON or OFF. It was replaced by another, new one (80's) and became a good girl.

Maybe your calculator has some extra current consumption in the circuitry, I don't know. If I have the chance to try, I'd disconnect the IR emitter (if I don't use the printer). If the driver is malfunctioning, there's a possibility (vague) that a current flow through the IR LED is killing your batteries.

If it is dying in use, I'd suggest checking for printer mode: if printing is ON (PON) and the calculator is in TRACE mode, every operation would activate the IR LED, that is somewhat power consuming.

Maybe it helps...

            
Re: 42s batteries
Message #3 Posted by Ellis Easley on 27 Mar 2002, 4:24 p.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

I wonder if your 15C ended up in a sidewalk sale in Dallas in 1994? That's where I got mine, for $30. It looked OK but went through batteries very quickly (< 1 week). I measured the current drain with an external power supply and it actually drew much more when it was off. I found the PCB was covered with corrosion, after cleaning the current drain was normal. It has worked fine since then, except it's not quite the same as new due to having been reassembled - I used a tiny drop of superglue for each of the heat-stake posts, one at a time, pressing the parts together with my fingers till the glue set.

            
Re: 42s batteries
Message #4 Posted by David Smith on 27 Mar 2002, 5:46 p.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)

I have a '42S draws 80mA on or off... batteries last around 3 hours. The problem lies in the big chip. Removing all of the other components changed nothing.

                  
Re: 42s batteries
Message #5 Posted by Ellis Easley on 30 Mar 2002, 5:38 p.m.,
in response to message #4 by David Smith

This reminds me of something - when I first went to work for Tandy repairing TRS-80 boards at the factory, there was a board with a cassette problem that several people had tried to fix without success. I removed all the electronic components and measured between traces with an ohmmeter on a high range. I found something like 4 Megohms between two adjacent traces, ran a scribe between the traces and it became an open circuit. I put new components in (everything had already been replaced at least once) and it was fixed. It was a high impedance circuit built around a 3900 "Norton" amplifier chip and apparently 4 Meg unbalanced things enough to make it fail.

Without knowing anything specific about the chip you're talking about - except that it is CMOS undoubtedly - if there was a pin with a 100-200Kohm internal pullup (or pulldown) and a leakage path of similar resistance to the opposite polarity on the PCB, the input would be in an illegal state and that single input pair of transistors could be drawing that current, and still be presenting a valid logic level to the internal circuitry

      
Re: 42s batteries
Message #6 Posted by Thibaut.be on 28 Mar 2002, 12:10 p.m.,
in response to message #1 by a

I work for a watches company, as many of you already know.

We own a swiss batteries brand, that for some reason I am not allowed to explicitely name here.

I can provide the 44 model batteries that are upon to my experience excellent for our calcs. They fot not only the 42 and similar models (32, 17BII, ...) but also the voyager series.

I will sell these batteries at no profit. But according to shipment costs it is better to order a more important quantity. Anyway the minimum quantity is 10.

This is very much interesting for european collectors as most of european countries have charged huge taxes on these.

I suggest, for any people showing interest on these, to click here for all details.

Good luck !

            
Re: 42s batteries
Message #7 Posted by Ellis Easley on 30 Mar 2002, 4:50 p.m.,
in response to message #6 by Thibaut.be

I can't connect to your website for some reason, and as I live in the U.S. probably wouldn't benefit, but I am curious about the price. Here, I can get them for $3 at Radio Shack, $2 at WalMart, or $1.29 at Fry's Electronics. At Radio Shack it is "their brand" which I think is made by Eveready. At WalMart it is Eveready brand, at Fry's it is Duracell. I'm not asking your brand, just telling you what these stores have. How much is the tax you have to pay? How much do your governments tax cigarettes? In the U.S. the states have raised cigarette taxes to high levels to raise revenue after winning lawsuits against the cigarette companies. In the process a few lawyers working for the governments have been paid billions of dollars. The only way I can make sense of it is that the cigarette companies have agreed not to sue for restraint of trade after the taxes were raised dramatically. The ironic thing is that in the U.S., most people who still smoke are in the lower income brackets, so "making big tobacco pay" has boiled down to a tax on the poor!

                  
Re: 42s batteries
Message #8 Posted by David Smith on 30 Mar 2002, 5:19 p.m.,
in response to message #7 by Ellis Easley

If you can find the "Vinnic" brand from China, you can get a card of 10 cells for around $2.50. They seem to work quite well. In the Dallas area Tanner Electronics sells them.

                        
Re: 42s batteries
Message #9 Posted by Ellis Easley on 30 Mar 2002, 5:50 p.m.,
in response to message #8 by David Smith

What's the westernmost Tanner Electronics store? I don't find them in the Fort Worth phone book, and most Arlington stores are in there.

                              
Re: 42s batteries
Message #10 Posted by David Smith on 31 Mar 2002, 4:51 p.m.,
in response to message #9 by Ellis Easley

Tanner only has one store. It is in Carrolton on Valwood, a little west of I35. He does not do mail order but I think BG Micro also has them. BG does mail order and shares a lot of items with Tanner.


[ Return to Index | Top of Index ]

Go back to the main exhibit hall