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

[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?