HP-34C Draining battery quickly


Any assistance is appreciated!

I purchased a "mint" 34C from ebay and have found that it empties the battery overnight. I've put in 2 replacement packs with the same results.

To ensure that the packs were fully charged, I've used a 3v precision charger to charge them and then inserted into the unit. It runs fine, but I power it off, come back in the morning and the battery is DEAD.

The reason for external charging was to take the 10VAC charger out of the equation.

I've searched for a schematic. I'm wondering if there is a diode shorted somewhere in the power circuit. I found a technique here to open the case using a piece of string, but this does not fully expose the circuit board. Not wanting to make things worse, I've decided to post this question before proceeding.


This link:
Spice Repair - Voidware is what you are looking for if you decide to access the circuit card.

Jeff Kearns


This could possibly be caused by some corrosion that has bridged between + and -

That is a guess on my part.

I've been pretty successful getting the case apart with an old credit or Plastic ID card. The thinner the better.

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