HP34C battery polarity

[Zaphod]

(05-07-2019 08:42 PM)burkhard Wrote:  I wager that the problem is that it is a Spice. Most of those were built using the innovative and stupid design of not soldering the chips to the board, but making electrical contact (usually, except when it doesn't) through case assembly clamping pressure.

A simple test that does not require opening it: With the batteries in and the switch turned "on", hold the top (display end) in one hand and the opposite end in the other hand. Exert a slight twisting torque first in one direction and then the other. Obviously, don't crank it far enough to crack anything, but a detectable degree or so of rotational displacement is in order. My bet is that it will suddenly come on, and will work for a while, until it needs to have the calculator chiropractor called in again.

Well done that man, I knew about the clamped style versions of these (as I had a HP31e back in the day which I disassembled and discovered)
That's why I mentioned the weight earlier.

Anyway a slight twist and I got a dot !........ a dot !!

So a very gentle tap on the desk and et voila - it's back !!

I will have to strip it sometime and clean up.... at least it's not anything too dramatic.

I'm enjoying the red led effect for now... eyes goes misty ........ ahhhhhh