Disassembly and Repair Notes for HP 41C Calculators


HP41C fullnut, serial number beginning with 23

This calculator had a few sticky buttons, which were successefully fixed. Disassembly pictures are found here.

Repairs made to this calculator:


HP41C fullnut, serial number beginning with 22

This calculator was a bit unstable and died on me a few times, but could be brought to life by grabbing the upper and lower end and twisting. Also, the display fades a little when pushing the below the display. The instability problem seem to be to have been solved by cleaning the internal pressure only contacts, but the display still tends to fade a little when pushed. Disassembly pictures are found here.

Repairs made to this calculator:


HP41CV fullnut, serial number beginning with 22

This calculator had a strange fault: if the lower end was lifted a few centimetres and dropped the figures in the display were replaced with rubish of the type you can generate if you store things in the alpha register with synthetic programming, and a few of the mode annunciators turned on as well. Cleaning the internal pressure contacts did not solve the problem. Inspecting the motherboard a cold solder was noted on the smaller of the two condensators seen in the upper left corner in the picture. Fixing this with a very small soldering iron solved the problem. (Note: the motherboard in the picture is from a 41C, but is similar.)

Repairs made to this calculator:

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