During last months I have collected some "scrap". I have four HP-41C calculators. One of them works just fine. I can´t turn on the other three. I have tried to swap the CPUs. The result is that the working CPU is ok in any case and the other three don´t work anywhere. So it is clear that the problem is the CPU, not contacts or displays. Any ideas?. May be there is a capacitor or something that fails in this model.
Sorry for my bad english, I hope you understand me.
Thanks in advance