How to fix an old HP41cx

[GreyUser]

Any plastic case repairs should be performed with solvent based plastic model cement, often times called plastic solvent cement or plastic welding solvent. Using cyanoacrylates (super glues) will result in failure 100% of the time. Attached is a photo of a repaired case back, the spacers are 1mm square by 7-8mm long. The size is not critical, they only need to fit into the recess of the battery contact block.

The bottom screws that hold the processor board in place need to be the 3/8" version (9.5mm). The shorter screws will result in broken and cracked posts. I doubt your 41CX has the shorter screws as that change would have been incorporated into standard production by the time the CX was produced.

Another possible issue that popped to mind about your failure description could be contamination of some kind on the processor board. It could be on the top or bottom, anything conductive in any way will cause problems due to the extremely low operating currents of the 41.

Do you know the history of this CX or did you receive it as-is, partialy/intermittantly functioning?