Help!! My 29C may need a doctor.


Hello all.

Wednesday, my 29C took a bit of a tumble. It was inside of a shoebox with my other calcs. The shoebox was inside of a totebag stuffed with other books so the shoebox couldn't move all that much. While I on the way home, the tote fell from the seat.

Today, when I turned it on and press the keys, it gives me odd values and even some hex. My other calcs, the 67, 35, 25 and 41CV seem to be fine.

I'm going to leave the battery pack out but I wonder if that solves the problem. I see that FixThatCalc is temporarily closed but, are there other options to see if my 29C is fixable? Or, will leaving the batteries out help?

***UPDATE ***

I just put the battery pack in and the 29C is still on the fritz.

So, although Randy at Fix That Calc is pretty busy, are there other options to have my 29C repaired?

Edited: 30 Mar 2012, 8:25 p.m.


Is it possible that you jarred the LED PCB off the row of spring-fingers that connect it to the main PCB? If so, you should easily be able to open the case (fortunately the screws are easy to get to under two of the rubber feet) and re-seat the LED PCB. It's been 15 years since I last took a Woodstock apart, but that is what I remember. Good luck. One would hate to loose an increasingly rare HP-29C.

A picture of the 29C internals showing what I describe is here. Also,
this this shows a similar Woodstock disassembled. You can see where the two screws are that you need to remove to open the case.

There's a similar set of spring-fingers that connect the keyboard. It would be worth re-seating all these sets of mechanical connections.

Edited: 30 Mar 2012, 8:48 p.m.


Hello all.

I'm not very coordinated and I'd be pleased if someone here might be able to help me on that.

I'd sincerely appreciate it.

Thank you.


0. Remove the battery. Watch out for static discharges to exposed circuitry.

1. The two rubber feet around the charger connection are really rubber plugs. You can gently pry them out without damage.

2. Under each of them you will find a Phillips screw. Remove those two screws.

3. You can now press inward on the two posts in the charger slot to push the top end of the keyboard panel away from the case. Then you can gently remove the whole keyboard/LED/main PCB assembly from the case.

4. Note that the keyboard attaches at top and bottom to the main PCB with two rows of spring-fingers (there's probably a better name for these). Just pull the keyboard away from the main PCB.

5. You'll notice at the top of the main PCB that the LED PCB is attached by a row of similar spring-fingers. Either push the LED PCB down to re-seat it fully (as far as it will go) on the 20 fingers, or pull it completely off from the main PCB, then re-seat it.

6. THERE IS NO STEP 6! :-)

7. Match up the keyboard to the main PCB fingers and re-seat it fully on the 9 fingers at the top and the 9 fingers at the bottom.

8. Put everything back in the lower case, apply the two screws, put the battery in and see if it works.

9. Re-install the two rubber feet/plugs.

Here is another member's explanation, as is this.

You might also find this article about the insides of a Woodstock of interest to review as well.

Pretty simple stuff. The Woodstocks are the easiest HP calculators to open that have ever been made.

Edited: 30 Mar 2012, 9:51 p.m.


Yes, I appreciate your encouragement and enthusiasm that I could do this but, I have no coordination or dexterity to accomplish these steps. Is there any here that would be able to repair my 29C, please?

Thank you

Edited: 30 Mar 2012, 10:03 p.m.


Hi Matt,
I might take a look at your baby, but I'm in Italy, but the shipping maybe are too expensive. I have repaired many HP calculator, all the classic series, all the Woodstock series (even a 27), topcat and many other.
Let me know if you want ship your calculator.

Regards from Sardinian island (Italy).


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