The system came with a matching Floppy Drive Unit that connects to the expansion unit. It uses an MPI B51 40 track single sided drive.
I gave it the routine clean and lube, but it would not read disks. Drive speed was good.
Configuration was preset:
I located a service manual on the net and that was very helpful for fault-finding.
I convinced myself that the differential amplifier (CA3054) in the read circuit was cactus and replaced it. With this, the system booted. Alas, it wouldn’t format disks.
Breaking out the CRO and checking the signals on the drive interface showed there were no index pulses. In an unexpected twist, it turned out that the disks i was using were not sufficiently opaque. Is that even possible?
It appears so from the traces; the voltage in the top picture never gets high enough to flip the comparator, whereas in the second picture, with a different disk, it does.
I checked over and over. It’s fine with five other brands, so I’ll call it good enough.
It lasted about a week before it stopped reading from disks. Perhaps it had an intermittent problem and the original differential amp didn’t fix it.
With the scope, I was able to see differential signals going into the LM311 comparator, but nothing coming out. I replaced the comparator and i was back in business.
I made up a few disks and had a play!
I also had no trouble setting up a gotek as a drive. I just powered it off the real drive and connected with a custom cable. It has to be set to drive 1.