Zenith H-100 Service Manual page 77

10-82
PROCEDURE
Obtain a calibration circuit board (see H-207 manual
HE 595-2909 for construction).
Connect the alligator clip of the calibration board to
a source of +5 volts on the H-207 controller board.
The positve end of any .1 uF glass capacitor is a good
source.
Connect the black wire from the calibration board to
the GND test point on the H-207 board.
Connect the yellow wire from the calibration board to
the CP3 test point of the H-207 board.
If not already done, set R3 fully counterclockwise and
R4 fully clockwise.
Set the jumper select wire of the calibration board to
120 nS. If the drive requires more precompensation,
set the jumper to the desired position.
Turn on the computer.
Boot up a system disk. Refer to the appropriate
operating system manual and start the disk format
program.
While the format program is running, adjust R3 on the
H-207 board until the LED on the calibration board just
turns on.
Turn off the computer and disconnect the calibration
circuit board.
This completes write precompensation adjustment.
NOTE: All diskettes should be reformatted before being
used.
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