Service Manual for SPICE series? (Dead 34C) (Repaired)

[Waon Shinyoe]

I got a very clean, very nice, but unfortunately completely dead 34C...
I have no idea what's wrong with it, and I couldn't find any chip info (pin definition, etc.) or internal design...
Any suggestions? I'm sure there is power.

[Waon Shinyoe]

* I think the problem should be the broken FPC that connects the battery terminals and the board. Will try to fix that with soldering.

[jebem]

If you search for hp spice repair here in the museum you should find some information.

The flex power cable is known to fail due to a number of reasons.
1. Battery leakage is the most common reason.
2. However the flex cable connection to the battery holder contacts can present high resistance due to aging (oxidation, dry electrolysis, you name it). Hp used metallic rivets as contacts, no soldering involved here, so we have two different metals pressed one against another.

I had the issue number two above on my Spice calculator.
Have used a ohmmeter to check the continuity and one of the battery contacts had high resistance (we need zero ohms here).

This is my 32e repair report:
http://www.hpmuseum.org/forum/thread-722...ight=Spice

Good luck with your repair.

[Waon Shinyoe]

Thank you Jose!
Here is a close shot of the broken FPC, which cause the negative terminal to float.
https://imgur.com/gallery/A2zxA

[Waon Shinyoe]

So I used a sand paper to expose the metal part from the FPC and soldered to the terminals (+ and -, there is another trace which I don't know where it connect).

When I inserted the batteries, the screen once showed 00000000 00, with no key response. After that, there is no display, even though there is power & clock signal.

Any idea what happened?

[Waon Shinyoe]

It works now. The second to last LED digit is missing, likely due to the battery leakage. The PRGM/RUN switch doesnt work well and requires a force applied to keep it in RUN mode. Otherwise, the HP-34C functions.

[jebem]

(03-01-2018 07:37 AM)Waon Shinyoe Wrote:  It works now. The second to last LED digit is missing, likely due to the battery leakage. The PRGM/RUN switch doesnt work well and requires a force applied to keep it in RUN mode. Otherwise, the HP-34C functions.

Glad to know you had success repairing it!

- To fix the remaining problems you would need to totally dismantle the calculator, piece by piece.
- Then inspect the electronic parts for remaining of battery electrolytes and use common vinegar to remove them using a soft clean brush and let it react for around 30 minutes.
- Next step, clean all components in abundant warm water with dish hand wash detergent and a soft brush. Then use abundant warm water to remove the detergent.
- Next step, apply abundant isopropyl alcohol (IPA) and use a soft brush to clean all the electronic components from remaining residues and water. Of course you need to use silicone gloves for this operation as IPA is slightly toxic on skin contact.
- Let the parts dry in a warm place for at least 24 hours. Do not use the home oven as the risk to deform the plastic parts is very high. Industrial/laboratory temperature controlled ovens could be used at around 40 degrees Celsius top.

- Before assembling the parts, visually inspect again the sliding switches contacts for oxidation.
The switch contacts can be clean with a good electronics contact cleaner. On severe cases, use sandpaper to lightly scrape/remove the oxid layer, then apply the contact cleaner.
Sometimes the problem is on the PCB itself, so you need a continuity meter to check for bad traces.

- The LCD could in fact be corroded internally on some segments wires and this would be impossible to repair.

Forgot to mention this important notice:
Do not use the external power charger without having a good battery pack installed in the calculator, or you risk to destroy the electronics. Another option is to use non-rechargeable primary batteries and forget about the calculator charger.

By the way, is you calculator solder-less like mine, or are the integrated circuits and LCD soldered to a conventional PCB?

[Waon Shinyoe]

Jose, thanks for your advice! Mine is a solderless model for European market (decimal point shows up as "," . There is also an "*" before the serial number.)

Update: Opened it, found the PRGM/RUN switch was broken (the metal part). Replaced it with a switch from a HP-33E. Everything works perfectly now, except the second to the last digit. Is it favourable to put the LED component in vinegar?

I'm wondering if I can make a replacement switch by myself. Or I will simply solder the 33E to keep it in ON mode when batteries are inserted.