[sebhc] Floppy drive circuit boards

dwight elvey dkelvey at hotmail.com
Fri Sep 22 09:38:33 CDT 2006

>From: "Mark Garlanger" <garlanger at gmail.com>
>Does anyone know if the circuit board (the one physically connected to
>a floppy drive) is calibrated (or otherwised tuned for the mechanical
>part of that particular drive? I have two of the Wangco model 82's
>that have different issues. The first one fails the seek test even at
>36 msec. The second pulls down the 12V supply line. I didn't know what
>could be done with the first one, so I attempted to fix the second
>one. It had an obvious burnt inductor 'L5'. But, from looking at the
>circuit diagram and what little I remember from EE, it didn't see how
>this would explain the problem with the 12V supply. So, maybe there
>are other damaged parts on the board.


It is possible that the inductor got burnt when something external
fell on the circuit board, like a screw or something.
If the short is still on the board, I have methods for finding the shorted
point but it does require a good 5 digit meter with a 200mv scale.
4 or 4.5 digit might work as well but not a 3 digit.
It might be that the short is layout related and not shown in the
As other say, I've swapped boards with no issues when I know the failure is
the PC board. Most motor speed controls on older drive use either a tach
or back emf from the motor. Both of these should be able to be used
from machine to machine with little change if the same part for the motor
is brought with it.

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