Hello All,

I've just got an used HP34C with leaked batteries in place corroding the connectors, the problem as many already know.

After open the case & clean the unit, I've powered it up and get the display running continuoustly
... sometime it stops after a while displaying : 000 -

informations about this unit :

- s/n 212043xxxx

- made in Singapore
unsoldered IC's

- Small IC's : ILB90002 - 1MA10014 - 1MA10015 (all have HP logo engraved)

- Large IC by AMI

Is It really need batteries connected to run ?

Any helps would be very appreciated.

Many Thanks,



After open the case & clean the unit, I've powered it up and get the display running continuoustly
Is It really need batteries connected to run ?

You may use it on batteries only. You MUST NOT power it up without good batteries inside. Else you will kill it, indicated by a running display. Many people did this experiment already, me too. Seems you are another one. Good luck next time!



The calculator undercharged overnight.

This morning, its display showing all 0's and not run continuoustly anymore.



Hello Pyerre,

Did you power it up with the Hp adapter or with a lab power supply ?

The thing needs 2,4 to 3V DC to run.




I've powered it up with the 82087B HP adapter
and new Ni-Mh batteries (not NiCad) inside

and thought that should have its own kind of batteries to work ?

correction : s/n 2120Sxxxxx

Many thanks,




For the time being, put aside the dreaded 82087B and the NiMh.

I suggest the following:

- check that all your ICs are correctly oriented (the notch towards the LED display)
- test with 2 normal alcaline AA 1.5V batteries WITHOUT the charger

and tell us how it goes.




Hello Etienne,

It displays all 0's !



If this display persists and the power supply circuit is not corroded/broken, then one or more chips have fried.

Do you have soldering equipment/ability ?



Hello Etienne,

> Do you have soldering equipment/ability ?

Yes, I do.

There's some corrosion at the pcb, but the ribbon cable looked like in good condition.

May I need to bypass the ribbon cable ?



Hello Pyerre,

No, I think the simplest way would be to adapt your display to a known working 34C board and discard your existing board as corrosion/adapter may have ruined the power supply along with some chips.

Therefore, I propose you contact me directly at EtienneREMOVESPAM.victoria@orange.fr.

I'll send you a working 34C board which is of the soldered type (more reliable one).

You'll have to save your display and solder it to the board and then readapt the whole stuff in your calculator enclosure.

Just drop me a mail if you are interested in trying this.


Edited: 2 June 2006, 10:27 a.m.


I am assuming that you opened up the keyboard sandwich and cleaned all the pads where the chips connect with alcohol, then got the chips back in the right places, and got the thing back together again correctly. If so then...

A display of all 00000000 is the classic symptom of a fried ACT chip in the Woodstock series of calculators. In a Spice calculator like the 34C, your big chip is probably fried.



Many thanks for your indication.

Just to be curious, is this ACT chip compatible and can be replaced by the one found in the Spice calculators serie ?



Just to be curious, is this ACT chip compatible and can be replaced by the one found in the Spice calculators serie ?

No. The ACT is a 22-pin chip, and the Spice series uses a 40-pin processor chip. The various Spice models use different variants of the processor chip, which are not interchangeable among all Spice models, though a few models do share a common chip.





Just to be curious again,

Is the 34C's big chip unique or it also be used for another Spice model, and which one if it's the case ?




The 32E, 34C, and 38C use an 1820-2162 or 1820-2162-A processor. I'm not sure whether there's any functional difference beteween these. They should be interchangeable in all three models unless there is a code difference in the 8-pin ROM chips that requires a specific processor variant (with -A or without).

They are not likely to be interchangeable with the other Spice models.

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