We usually get questions about repairing defective HP41c. It is usually Ignacio who repairs them, since he is much more knowledgeable than any other I know; but there are many repairs that can be performed by anyone of you - if you just dared to open the calculator. Let’s discuss the different cases, and tell what is difficult to repair from what is easy.
Rust in the battery contacts. This is one of the repairs that I would consider easy, and that can be done by any of you. Please refer to this product in the website
Calculator would not start, but the battery contacts are OK. First check battery polarity. Second, is your calculator a full nut (square screen corners) or half nut (round screen corners). If full nut (meaning it has two circuits, pressed one agains the other by the two lower screws that are hidden by the rubber pieces. This is by far the most frequent problem, and it is called “broken lower posts”. These can be easily repaired by yourself (unless someone else tried before and destroyed the assembly). This is many times one of the most satisfactory repair: a little glue, a little time waiting for it to cure, assemble it back, and voilà - a previously lost calculator is back at work
Screen problems. It can be easy or difficult. If there is a black part of the screen, consider it difficult - you’ll have to get a donor for the screen, and the soldering and desoldering involved is not for the faint-hearted. If there is a blurred set of segments, it may suffice with cleaning the PCB and making sure that the circuit connects well to the main board - that may solve the issue.
Keyboard issues. Can be easy or difficult, but it is worth trying it yourself to check. There are different kind of issues: bad contacts and bad clicking action of the keys (some times can be cured with cleaning -easy- but other times the key dome is broken -difficult and a donor is required). In general, opening, cleaning and adjusting it is good practice and doesn’t damage anything.
Finally, if the repair didn’t work, or you feel you can’t do it yourself, you can always contact Ignacio through us: firstname.lastname@example.org