My old computer gear-- Any interest?

From: Joe <rigdonj_at_cfl.rr.com>
Date: Mon Dec 23 16:26:00 2002

At 03:24 PM 12/22/02 -0500, Charles wrote:
>
>
>The power module cable is a problem though. The wires in the cable seem
>to break at the molded connector on the calculator end. I have two
>calculators and three power modules. I can only get one of the power
>modules to work most of the the time. I will have to try rebuilding the
>battery packs. All of them I have are shot.

   Are you talking about HP-35 type claculators or HP-25s? I've never seen a cable problem on the chargers for the HP-25 but I've seen lots of problems with the HP-35 type chargers that use three wires. But they can be fixed. First you need to open the charger and figure out exactly which wire (or wires!) are broken. They will almost certainly be broken where the wires enter the molder plastic plug. You'll have to cut back the plug and slit open the wire insulation until you find the break. The break is usually easy to find because the wire will be very flexible at the break. Then I cut the insulation back about 1/8" past the broken ends and solder a short piece of very flexible wire to the ends. (I use a J hook to make they have a good connection that will resist the pull on the wires.) After I get them working, I wrap the joint with unwaxed dental floss (high strength nylon cord) and coat it liberally with the plastic potting compound that's used to coat plier handles. I zig zag the dental floss back and
forth past the joint to try and give the joint some reinforcement. You can't go far on the molded plastic plug but you can wrap the cord over the bulges so that it has some place to attach. I've fixed DOZENS of chargers this way and my success rate is about 98%.

  Both the HP 35 type calculators (aka classic series) and the HP-25 type both use AA size NiCads and are fairly easy to rebuild. But you'll have to reuse the contacts on the 35 type packs and they need to be spot welded to the cell so you'll probably have to find someone that has a battery spot welder. Anyone that builds or rebuilds battery packs should have one. Batteries Plus is one company that comes to mind. They seem to be wide spread. Beware of some of these companies. Some of their prices are outragous. I went to an Interstate battery store a couple of weeks ago and they quoted me almost $100 to rebuild a five cell battery! I told them they were out of their minds. That job shouldn't cost more than $20. The battery wholesaler that I use to do business with charged about $2.50 each for AA size Sanyo NiCads and $.50 for each strap that they welded on. That would come to about $11.50 for a HP-35 type battery and that's using GOOD Japanese made Sanyo cells.

  Batteries. I INSIST on Japanese made Sanyo cells! I've tried a lot of other brands and found most of them are JUNK! I haven't found ANY good American made, Chinese made or Mexican made cells including the Mexican made Sanyos. I've heard that some of the other Japanese made cells are good but I haven't tried them. I've had EXTREMELY good luck with the Japanese made Sanyos. I've rebuild hundreds of battery packs with them and I think I've only had one cell fail. I've also got a set of four AA Sanyos that I bought in Thailand in 1973 and they're still working fine!

  Joe
Received on Mon Dec 23 2002 - 16:26:00 GMT