One of my 41's doesn't like modules in port 4

[Harald]

(05-07-2016 08:07 PM)damaltor Wrote:  Interesting. I am a bit scared to open it though, because it is one of the very early ones with the delicate connection between the pcbs.

I am not sure which voltages are present on the expansion port. But maybe someone else has information on that? You could at least measure those that are accesible wirhout opening the calculator. Maybe that will give you a clue as to what is going on.