-=> Thom Kouwenhoven said to Greg Mayman
 -=> about "VEHICLE LED'S" on 10-24-03  19:41.....

 TK> I wonder if my reasonbly new 3.5" floppydrive could be the problem.

It's always a possibility.

A slightly lower sensitivity in the read/write head, and/or
slightly lower gain in the preamplifier, would make it more prone
to missing some bits. And a slightly higher sensistivity and/or
gain would make it more prone to noise.

And these days, it is almost impossible to measure signals inside
the circuitry of the drive, even if we knew where to look and
what to expect.

The first floppy disk drive I ever saw had a pile of presets on
the PCB to set the gain of the preamp, the sensitivity and
threshold of the Schmitt Trigger detector, and so on. And a heap
of test points where you could connect a CRO to check the setup.

There was even a special floppy disk supplied that was recorded
excentrically, so the tracks weaved under the head. You were
supposed to set the head stepper mechanism so the preamp output
showed a two peaks of signal for each revolution of the disk.

Gee, those days are long gone. Nowadays it either works or it
doesn't, and you can't do a dern thing about it :-(

From Greg Mayman, in beautiful Adelaide, South Australia
   "Queen City of The South"    34:55 S  138:36 E

... If it ain't broke, let me have a shot at it.
___ Blue Wave/386 v2.30

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