Spice series issues



#2

Pardon my ignorance as I am sure this is old hat for most of you but I recently came into quite a few 1970s HP Calculators and am in the process of evaluating them for functionality. All seem fine for the most part except the Spice series, none of which power up. I have tried several power supplies and some do nothing while otheres just flash random numbers. Is it possibly because I have no batteries for these and am trying to turn them on with only the power supply connected? I got no battery packs for these and am also wondering where I should get them if available. I searched the trouble shooting on this web site and found no battery info pertaining to shis series.


#3

Spice + power supply + no battery = dead unit.

You've likely been destroying each as you test.
Well those that aren't already dead and gone...


- Pauli


#4

I wasn't aware that the Spice series had the same poorly designed battery charging circuitry as the Woodstock models. Damn! You know there should be a special place in Hell for the person or persons responsible for this charging circuit design. The upper managment personnel that approved the design should also join them.


#5

Its possible I'm mistaken on this one but I do remember being warned to not run a spice without batteries.

- Pauli


#6

All the Spice manuals (handbooks) have a note regarding ac operation: "Do not attempt to operate the calculator from the ac line with the battery pack removed." Now, they do not specify what the consequences will be if this is done, but for sure the calculator will not function properly. Whether this can or will also result in irreversible damage to the calculator, I do not know, however, I think it is prudent not to find out.

#7

First off, you can't power these using the AC adapter, because it is a battery charger only, and the circuit requires that a good rechargeable battery be installed when you attach the adapter. The calculator can ONLY be powered by applying 2.5 Vdc to the two battery contacts inside the battery compartment. The polarity is (-) on top contact and (+) on bottom contact. You can do this by insertion of 2 AA cells with proper polarity and a jumper on the opposite site to connect them in series (be careful not to damage the contacts as you can deform or break them if they are compressed too much, since AA's are taller than the flat top cells used in a proper battery pack), or you can use a DC power supply if you have one. NiCd battery packs can be bought on eBay from Waterhosko (Mark Hoskins) for $9.50 including shipping.


#8

I have found that the +ve terminals of the batteries can be hammered in (with care) to get them to fit.


#9

Oops. I don't mean hammer them into the calculator. I mean hammer in as in standing the battery on the -ve end and gently hammer the +ve terminal in slightly. It only has to be hammered in about .5MM ie not much. Tap and then test and tap again if needed.


#10

From what I can tell, a typical alkaline AA cell is 50.5mm tall, whereas a NiCd flat top AA is 48mm, so the difference is more like 2.5mm. Pushing the battery contacts an extra 0.5mm isn't going to hurt them, but an extra 2.5mm probably will. Even if you pound the positive tip all the way in, the cell will still be longer, because the body itself is also longer.

The battery contact design on the Spices is about as stupid as it gets, because they are almost guaranteed to break after a number of battery removals and insertions, unless the user is extremely careful and gentle. The contact has a very sharp bend, such that the material has already been taken past the elastic limit (yield point), and just a few stress reversals will break it off at that location. All HP had to do was form it with a gradual bend, and this failure would not occur. Also, the rivetted connection with the circuit board tends to get loose over time, resulting in a bad electrical connection. Even after HP fixed the solderless design issues, they still retained this faulty battery contact design, so finding a good Spice of any vintage remains a challenge.


#11

Wonderful....case closed. Thank you all for the very useful information.

One of the other units was a 97 that would only run once I removed the battery pack. So based on that I felt safe trying these without batteries.

I was able to rig a test with a couple double A's and in the name of research have discovered that preliminary testing seems to indicate many have survived my ignorant fiddling. Surprising considering the output of the "battery charger." One unit still shows only odd characters and I was unable to test two yet due to already broken battery tabs. One unit, a 38E, is completely dead but I have another 38E that seems to work fine so my assumption would be that it was done previous to my abuse. Based on that assumption I have a survival rate of 75%.

Thanks again to all for your helpful advice.

Kevin


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