A soldered HP-33C repaired.


This calculator was not used for a long time with the batteries left inside. It was not functional when I received it and the battery contacts showed traces of leaking batteries. One battery contact was broken.

To observe the internal damage caused by the leaking batteries the calculator had to be opened.

It turned out to be a soldered version of a Spice series calculator. The foil from the power supply to the battery contacts was affected and some traces were broken. I removed this part of the foil.

HP33E_1 HP33E_2

The pictures above show the internal of this HP-33C calculator. To use the same housing as the non soldered spice models, a plastic frame is added. This frame presses the pcb with the keyboard towards the front. The right picture shows the print with the soldered chips. The power supply is still build on the same separate pcb. Also the LED display is soldered to the main pcb

HP33E_3 HP33E_4

These pictures show the keyboard side of the pcb. The keyboard is covered with a sheet of foam. When this foam is removed the key domes become visible.

Calculator showed weird behavior. It displayed all 0's, and didn't react on key presses. It turned out to be bad contact of the power switch. The switches were cleaned with IPA. The calculator works fine again. Still needs to add second battery contact and wiring from supply print to battery contacts.


Spice repair related links: