SPICE battery adapter

[Alevin]

I would like to share my recent experience in a HP-34C (non soldered) about a simple solution, minimal intrusive, for the battery compartment rehabilitation in spice series calculator, in the very special case one is lucky enought, and the only serious issue is broken contact tabs.

Previously, to open the calculator, after unsuccessfully trying the other methods (I did not play much with the knife method, as the HP-34C was pristine, and I did not want to get marks form the sharp edge of the blade), I succeed with the dental floss loop, technique, which description should be improved in to aspects:

a) Be careful to pass the dental floss line, previous to tie a loop, from one side to the other of the semi opened calculator below the location were battery connector wires are soldered to calculator PCB, or be sure to pass it above the fragile assemble of battery connector plate and wires.

b) Just pulling the dental floss loop away from the calculator did not work for me. I had to pull with some vertical component aswell. So, pull at 30-45 º from the horizontal, being the calculator lying horizontally on the frontal side.

Going to the battery compartment.

I was lucky as the battery connector line had minimal corrosion. The most of the damage was located in the plastic piece carrying the battery contacts, that had accumulated hard solidify leaks components from the dead batteries, easy to remove with a X-Acto stile razor and vinegar*. Nevertheless, the tabs were broken (see pics).

The original battery metal bracket was present. I got AA batteries (NiHm)

Example here

that have flat tops, and incorporated flexible soldering tabs (see pics), and introduce them in the bracket holder.

Locating and bending this tabs properly, which only took a couple of trials, I got a solid contact with the remains of the calculator cobtact tabs. The battery pack went in place smoohtly and without introducing any stress in the case. I kept the battery tabs in the front and rear part of the batteries, as they helps to keep a slight spring tension of the ensemble. Therefore, being in mind that minimal corrosion was found in the battery adaparter wire lines, it was possible to keep all the original components, and with minimal intervention the Hp-34C came again to life.

Nevertheless I plan to get a convenient Panamatik repair kit, as they are still available, just in case it could be needed in future.


*I had also to clean the on-off switch contact, as some black substance was disrupting the conduction on the cooper spring.