Restoring a HP9830B calculator.

[MattisLind]

Tape drive working!
The HP9866 was very dusty indeed. Before applying power to it I reformed the capacitors. They were all in excellent shape. So I started it up. No immediate problems. The LOAD button worked and I was able to load paper in it.

Hooked it up with the 9830. It was a no go. However since both tape and printer is dependent on the IO board in the processor I switched in the board from the HP9810A machine. Well, it didn't help much to the printer, but the tape drive started to work! Board swapping is not the a permanent solution but it is indeed a very quick way to isolate a failing board.

I was able to execute the MARK command successfully, i.e. it stopped after a while instead of winding to the end of the tape leaving the machine dead. It could store a small BASIC program to the tape and the LOAD it back! I think that the machine now is fully functional, although I have in all three faulty processor boards that need fixing.

Then the printer needs to be fixed as well. The good thing is that with the printer is not as crammed as the calculator it self which makes it a lot easier to attach the logic analyzer probes.