Restoring a HP9830B calculator.

[MattisLind]

BOT sensor

Well. I thought replacing the filament lamp with a LED was working all right. It turned out that it probably was to bright. It made that EOT/BOT LDR to make false positives.

I recognized this as when it did stop in the middle of the tape when rewinding and I pressed (and held down) the rewind button it just rewound very slowly (exactly as it did when on leader). Then when ejecting the cassette and replacing it again it started to rewind just fine for a while. I guess that the tape was slightly differently positioned with this maneuver.

Anyway. What I did was to increase the resistor value.

So, Tony, you were spot on!

Now it can rewind the entire cassette many times in a row without stopping in the middle.

But still the MARK commands goes on for ever (until blank leader at EOT) and then the machine is completely hung. The other tape commands just give a ERROR 58.

I am about to get some extender card to actually be able to attach the logic analyzer probes. Those different connector size are pretty annoying... six or seven different extender cards are needed to cover the entire machine.

BTW. The write protect and door switches are actually working, at least when pressing them manually.