Cromemco System Three PerSci 8" Drive Problem ?
Watzman at neo.rr.com
Sun Oct 28 18:07:36 CDT 2007
Disk detection on the Persci 270 series drives (and I think on the 299
series drives as well) is simply a microswitch triggered by the leading edge
of the diskette.
There are NO electronics in the insert detection / clamp / eject mechanism.
It is a trivial circuit consisting ONLY of a DC electric motor (24 volts, I
think) and 4 microswitches (two of these are operated by cams on the motor
shaft, one is the front panel eject switch and one is triggered by the
diskette itself when it's pushed in). All you need to troubleshoot it is a
multimeter. It has no connection to the actual "electronics" of the drive.
It's just straight DC electricity. Schematics are available on the Harte
site and in other places if you don't have the manuals.
The only thing different about the CS3 implementation is that they removed
the front bezel of the drives, and then replaced the eject switches that had
been part of the drive's own front bezel (now removed) with a switch on the
CS3 chassis. I don't remember if they connected this through the switch
wires left over from the (removed) Persci front bezel or if they did eject
through the 50-pin data interface connector (Persci did allow an eject
function through the 50-pin data cable).
More information about the cctech