How to fix an old HP41cx

[brmarcant]

(06-06-2020 02:22 PM)GreyUser Wrote:  That’s in decent shape, hardly a mess. The zebra connectors for the processor board are fine with nothing missing. The case bottom is a bit rough and it is missing the two upper battery connector locator/centering pins. That can be repaired with some styrene bar glued into place but it’s not the issue with intermittent behavior.

The bigger issue is your described problem. Since the bottom posts are sound, it sounds like a defective rom or ram chip on the processor board. The only way to troubleshoot is to substitute the processor board, this will tell you if the original board is the problem. To repair a bad rom/ram, you would need a service module and a donor processor board for the replacement ic’s.

Hi , thanks a lot for suggestions. But I want to be a bit more precise in the problem description. The calculator switched on several times. And I was also able to make some simple program. But moving it or continuously playing with it caused the system to switched off. Also keys doesn’t work all properly. The left line of keys looked to be a bit more unstable in working.
Do you still suggests that is a Rom problem rather than a contacts problem ?

Also got the styrene bar do you have any suggestion on how to repair it ?

Thanks a lot :-)