10 Oct
2005
10 Oct
'05
9:23 a.m.
One thing I have on my bench which is very handy, is
the PC has modified drive
cable which brings drive 'B' out to a 37-pin 'D' connector on the back,
and
a plug-in cable to allow me to easily connect external drives. I use this both
for testing drives, and for imaging from/to 5.25" and 8" drives.
I hve a commercial drive tester that uses the same sort of idea. There
are extension cables that you connect to the Drive B signal connector and
power connecotr, and route them outside the PC to the drive under test.
And a little box containing a microcontroller, ADC, and a frw other bits
that you connect to the PC's serial port (it takes its power from there).
And some MS-DOS software to control the whole thing.
You run the software and select the type of drive you're working on (it
has a large datahase of these, but alas no 3" ones, I think it does cover
8", and certainly covers 5.25" and 3.5", including the old Sony 600rpm
ones, and the PS/2 ones, for which you need cable adapters which I don't
bave). The software then displays a picture of the drive PCB (drawn with
the IBM line-drawing characters, even I can use this on an MDA
display...) which shows where to connect the clip leads from the ADC box.
I can't remember what they all are, but 2 of them go to the differential
amplifier output testpoints in the read circuit, one goes to the track0
sensor, one to the index sensor, and so on.
Yo uput an alignment disk -- a real analogue catseye disk -- in the drive
under test. It'll do things like move the head to the alignment track,
then use the ADC box to work out (from the signals on the read amplifier
outputs) how far the head is out of alignment. You can essentially do a
'propper' drive alignment without a 'scope.
I rarely use it, though. I have a normal drive exerciser and a 'scope,
and find those easier to fit on the bench than a PC.
-tony