Restoring a HP9830B calculator.

[MattisLind]

Running again

The programmed 82S126 chip arrived from Bulgaria today. Nikolay had done a good job programming it. I checked it in my DATA I/O and it verified OK.
Soldering into place on the boards and my HP9830B was back to life again! It was now able to calculate things.

Now I was able to continue where I stopped when it all started to fail; getting the tape drive to work. Unfortunately it wasn't working very well.
The MARK command still made it spin for ever and when it eventually stopped the machine was completely hung. A power cycle was needed to recover.

With most of the tape on the right spool REWIND only made it rewind for short moments until it stopped again. It might be that the friction between tape and head is to high. This type of problem has happened when I was repairing a DEC TU60 which is very similar.

Doing all sorts of other tape commands, like TLIST, STORE, FIND etc gave a ERROR 58 which seems to be some kind of general fault. And this happens immediately. It is not even trying to do something.
There has to be something weird with the tape unit itself or the controller logic. Need more investigation!
I am a little bit confused by fact that the MARK command executes but never stops. What is the machine waiting for to happen? Since REWIND is working I think that the EOT/BOT LDR detector is working.