HP-34C Old vs. New Version Spice


Is there an easy way to tell, without weighing or disassembly, if a Spice-model calculator is an early model in which the ICs are pressed to the PCB, or a later model with soldered ICs? Perhaps there's a known serial number date above which the soldered ICs were used. I have a late 1981 HP-34C (2134Sxxxxx) that I believe utilizes the later assembly method. I don't have any other Spice models for comparison. As far as I can find, the HP Museum doesn't have this information.



Is there an easy way to tell, without weighing or disassembly

In a word, no. Well, maybe no is too strong a word... but...serial numbers are meaningless as many units with low numbers sent for repair had their internals swapped out. Additionally, the change over date varied by model and nobody knows for sure what they are. Also consider that you have both USA and Singapore manufacturing thrown in to further muddy the water.

Weighing them is by far the best non-contact method but since you want a different approach, I would say it is touchy feely time. Go grab a 41 if you have one, fullnuts only please.

Once you know what to look for, or more correctly, what to feel for, you can tell instantly by pressing keys. The pressure fit models have almost twice the key travel, that is, from start of press to it bottoming out. They also require more pressure to get the switch to go over center. The soldered models have that great HP keyboard action since they were in fact a repackaged form of the 41 keyboard. Estimate the force required to press the 41's keys, if the Spice needs more and it has a harder click sound, it's a pressure fit keyboard. Subjective for sure but it's pretty reliable since the difference is really that big. Personally, I think the early Spice keyboard feel is among worst they ever made. This series represents one serious effort to remove manufacturing costs and it really shows.

FWIW, based on my data, a 34C with a 2134S serial should be a soldered unit, assuming it is all original. It's was made late in the game in Singapore, the only place where the soldered units were made.

This is just my opinion but I've seen more soldered 34C's then all the other models combined.


Thanks for that good info, Randy. I have a dead HP-41CV in my office that has a 2142Sxxxxxx serial (two months later than my HP-34C). The keyboard "feel" of the 34C is close to that of the 41CV.

I've acquired more than 25 different HP calculators since I bought a HP-67 new in 1977. My recently acquired HP-34C is the first "Spice" model in my collection. I believe that it fairly represents the high point in LED-display HP calculator functionality. But the noticably flimsy mechanical characteristics of the Spice units, compared to the Classic or Woodstock series, is unfortunate.


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