Spice restoration continue, or, how to open a spice without damage!

Hello again,

To start, I hesitated to repair and restore my spice units until I read or developed a technique to separate the two calculator shells. I have seen described a pull apart method with a lot of force used and deformation to the polycarbonate case. Hence the following posting.

I have used this method succesfully on 5 out of 5 spices. It did take one almost destroyed unit to figure this out. Actually the unit came in a total mess and the only salvageable stuff was the LED panel (solderless), battery hatch and battery hatch ribbon.

Obviously HP had an easy way to get into a spice, apart from the pry and pull and push method that makes one very reticent to work on one of these.

After careful examination of the case I have created the following steps to get in.

Of course, the obvious, looking at the back of the calculator or bottom shell we see the battery hatch. Unlike other HP's there are no hidden screws (figure 1).


Remove the hatch and you will see two screws (figure 2), remove these.


Once the screws are removed, grasp the calcuator and lift apart the two halves at the battery end (figure 3). The calculator will pivot around the foot of the two shells. Only pull the calculator apart as far as the figure indicates.


Now that the two parts are separated at the top of the calculator, insert a long and extremely thin knife blade into the seam which separates the shells at the foot of the calculator (figure 4). The seam is vertical to the longitudinal plane of the calculator. That is, the bottom shell fits inside a lip of the top shell. The knife must be inserted vertically for a very shallow depth (1mm) and then turned horizontally. This has the affect of lifting the bottom shell out of the upper shell lip at the foot of the calculator. You will see why this is important soon.


Now that the bottom shell is above the lip of the top shell and while keeping the knife in place to keep the bottom shell out of the top shell recess, give the calculator shells a twist (figure 5). This is a horizontal twist; each shell in the opposite direction of the other. Be gentle as this method does not require force.


In figure 6 we can see that the bottom shell now protrudes past the top shell. Refering to figure 5 again, and while still applying a twisting moment as described, give the knife a gentle twist. This will pry apart the bottom shell and top shell. This combined with the twisting moment you are applying to the case will release the internal latch mechanism. The mechanism will release with a quiet snap.


In figure 7 you can see the L shaped latch which causes the headache, well, maybe not any more! Arrow 1 shows the direction of the twisting moment applies on the latch with the knife in place and the bottom shell raised out of the lip. Arrow two shows the final twisting moment of the kife releasing the two halves.


Of course it is difficult to describe but in summary:

1.  remove screws
2. insert flat blade at foot of calculator to raise the bottom
shell out of it's recess (lip) in the top shell
3. while the blade is in place and the bottom shell is raised;
give the two shells a rotational twist which will raise the
rest of the bottom shell out of the recess
4. give the knife a rotational twist while still applying the
rotational twist to the two shells
5. you should hear a gentle satisfying snap as the L shaped latch
separates from its anchor point.

It's that easy!!

Cheers, Geoff

Edited: 27 May 2009, 3:37 p.m. after one or more responses were posted



Another tour de force from you! You should write a book on HP calculator restoration and repair. I've opened a number of Spices (spicem?) by the traditional "hope and pray it don't break brute force method" and while I've never broken one outright, in a few cases I did chip some material off the front of the top shell due to prying action from the bottom shell. Your method should prevent this.

Now, how about doing one with photo-illustrations on HP-65/67/97 HP-41C/V/X cardreader clutch repair?




Hi Michael,

Thanks for the kudo's!

In fact I have done a 35 page monogram on an HP65 calculator including card reader as an addendum for a book by another author.

However, in discussion with the author, the addendum will be converted into a stand alone HP restoration guide encompassing the classics, 41c's, woodstocks, spices, 48's, cricket, 71B's and whatever else I get my hands into.

I was wondering if there would be a small market for an on demand 'restoration' booklet covering the various models?

If you can make it to the HCC 2009 conference in Vancouver, Washington, I will be presenting a paper on HP 41C restoration including card reader in honour of the 25th anniversary of the 41. That is the theme for the meet this year. I am sure that the paper will be included in any subsequent disc from the meeting or will be made available. Included will be an HPIL lab set up by Richard Nelson and myself with help from others so if anyone is an HP 41 fan this is the place to be in October.

At the moment there are excellent sources in the repair section and by googling 'HP 67 card reader repair". These are extremely well written and documented.

Now for my next project!

Edited: 27 May 2009, 4:10 p.m.


Geoff --

Much appreciation for your recent postings with excellent photography and documentation regarding restoration of Spice-series calculators. They should be posted in the Articles section.

Almost seven years ago, I posted a technique using dental floss to separate the case halves. The objective is to detach the L-shaped latch from the other half without breakage. It worked well.


-- KS

Edited: 28 May 2009, 5:52 a.m.


Geoff (and all),

If there's a booklet available, I'll be the first one to send in an order!!!

Joel Setton


Thanks for the vote Joel! Yes there will be a book or booklet spanning most of the HP families!

Cheers, Geoff



I will try your floss technique and will include it in the Spice chapter (with credit to you) along with my technique in the book that I hope to prepare for the fall (maybe to ambitious at the moment but it will be done).

Cheers, Geoff


Many thanks Geoff
I have a 34C (1979 - Old Version) that seems great at the moment but I am always rather scared it might fail... I'll store this information for when I might (hopefully not) need it.

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