hp 34c continuous mem


I recently bought a 34c as a backup, but with no manual. The batteries have been out for a long time, and I have lost the continuous memory. My manual for 15c is not helping.

Can anyone help?




The loss of continuous memory is only the result of having left the calculator turned off for who-knows-how-long. All you need to do is recharge the batteries and (if the batteries are still in working order), you'll again have continuous memory.

("Continuous memory" is just what HP did so the calculator doesn't suffer from amnesia when you turn it off.)

If the batteries are no good anymore, you'll have to replace them or, more likely, rebuild them, since the 34C is no longer in production.



Thanks, Ernie.

Yes we have new batteries. But that did not do it.

The seller said that this item had been in a drawer for some time. She found it in her fathers stuff.

I vaguely remember from many years ago, when I had a 33E, that there was a punch sequence which you could use to restore this after the batteries had been out for too long.

Each time I turn the unit on, it comes on with a pwr error, which clears when you "clr X" or hit ant other key. All is normal, excepting that the display is in four decimals "0.0000", and you must set up at each turn-on, the number of decimal points, and the type of notation--e.i. sci, fixed, or eng. The thing dosen't which setting which you had it in when yoy turned it off.

My memory could be faulty, so would welcome any opinions.

Again, Thanks


Hi, Herbert;

for what I can think of possible faults:

1 - Power board with faulty component - If I am not wrong, all C-type Spices (HP33C, HP34C and HP38C) have a few extra components in the power board to provide continuous memory; some contributors in here (I remember Katie Wasserman as a first reference) have already dealt with this power board and they may give you guidance;

2 - IF the calculator has already been opened AND it is a solderless Spice, chances are that it's been disassembled and reassembled with the ROM/RAM chips out of order. The fact is that the HP34C has at least one RAM chip and this chip must be positioned in the correct "chip slot", otherwise you'll always have a [Pr Error] when you turn it off and on again. No damage if the chips are mounted following the correct orientation, but if the "privileged" chip mounted in the "continuous power supply" position is a ROM chip instead of the RAM chip, then... [Pr Error]!

Have you performed the [STO][ENTER] internal test? If not, please do it, and check for a

display. If you need guidance to open the calculator and check for this possible fault, let us know.

BTW, there are two major Spices' assembly types: the solderless (main logic components touch a flex circuit board in a "sandwich"-like assembly) and the soldered one (main logic components are soldered in a regular PCB). The best way to know which type is yours is by comparing: the soldered-type units WITH batteries are about the same weight the solderless-type units WITHOUT batteries, because they have an extra rigid metal plate to assure flex-circuit "physical linearity", if I can say so. Another way to compare is by carefully pressing the keys. Keys in soldered-type units move just a little bit in order to operate, while keys in solderless-type units almost level themselves with the keyboard faceplate to operate. If you can compare different units, it's easier to "feel" the difference.

I know that by tracking serial # it is possible to check for internal construction type, but I have no information about serial numbers, sorry. Anyway, the back case of any Spice fits in any other, so if the calculator has already been repaired or refurbished outside HP, there's no guarantee that the serial number actually follows internal construction.

I hope I did not confuse you; if so, forgive and post again, so we can find a better way to help you.

Cheers and success.

Luiz (Brazil)

Edited: 22 Mar 2004, 2:05 a.m.


Hey Herb, save yourself the trouble of re-building the batteries. I'm using Alkaline batteries in my 33E and i've had them in it for 3 months with about 1/2 hr to 3/4 hr per day usage (turning off when not being used of course) for the cost of two AA alkaline batteries, why bother????
Don't you agree???

Best of luck



Hi Paul. I too use 2 AA batteries in my 34C. I got ~ 3 years out of the first set and I have been on the second set for a year now. I use the calculator between 30 minutes and 1 hour each week.


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