21 Feb
2003
21 Feb
'03
6 a.m.
I just bought this
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=25399&
item=2507112537> off of E-bay. Obviously it's some kind of disk drive
tester. I opened it up and the entire front panel is hand wired but I
also found a commercail circuit board in it. On the board it says "MFD
Checker II" "Sony" "Made in Japan". Does anyone know anything
about a
Sounds like a standard floppy drive exerciser. The schematic might well
be in the service manaul for the appropriate Sony drive -- there is one
in the manual for the single-sided 3.5" drive, for example
MFD suggests Micro Floppy Drive (or Disk) -- Sony's name for 3.5" drives.
MFD checker? It looks as though the circuit board was
once the major
part of another machine and that they took the switches, displays and
Actually, the original drive exerciser was just a PCB with the switches
and indecators on it. No case. I guess somebody decided to box one up.
indicator lights off of it and rerouted them to the
front panel. However
there are a few things that they didn't put on the front panel; a 80 vs
70 track select (yeah 70 track), a drive select, a 300 vs 600 RPM select
I think some of the Single Sided drives were 70 track... And of course
the early 3.5" drives were 600 rpm.
and a good number of test points such as the write
gate. However on the
front panel you can now select 2MHz, 1 MHz, 500kHz, 250kHz, 125kHz or
67.5kHz. Anybody know what that's about? I'm guessing that it controls
Testing the write functions of a floppy drive is done by applying a
suitable freqeucny square wave to the write data pin and seeing how well
it records on the disk. Normally, you need 2 frequences -- the data rate,
and twice the data rate (that's the 1F and 2F on the orignal PCB). Sounds
like this unit was exteded to allow you to use other frequencies.
the bit frequency that's written to the disk and
that it's used to test
the disk coercivity. On the original board you could only select 1F or
It's not normaly to test coercivity with a thing like this. It's a tester
for the drive, not the disk.
2F. I should add that a 2nd baord as also been added
into the case.
It's a handwrapped vector board with 20 SSI ICs. I'm sure that it's used
to generate and select the extra frequencies and other as yet unknown
functions.
Suceh testers are very useful if you get to fix floppy drives. They'll
let you move the heads to the correct track to read the head alignment
pattern, etc. You do, of course, also need an alignment disk for this.
The tester also geneerates the correct signals to check each section of
the drive logic -- you can normally change the state of each of the
inputs to the drive, monitor the outputs, etc. If you suspect, say, the
track 0 sensor is malfunctioning, you can look at the trk00 pin on the
interface while moving the head around. If it doesn't change state when
it should, then you can dive into the drive with a 'scope and look at the
signals in the trk00 circuit.
-tony