Zenith H-100 Service Manual page 80

5-164
J2
=
8 > 5 PROCEDURE
Remove the controller board from the computer.
Refer to the H-207 J2 location pictorial and cut the
foil that connects the middle of the J2 position
to the 8
<
5 position of J2.
H-207 Controller
Board J2 Location
the middle hole of the
Install the floppy board into the computer.
Connect the oscilloscope probe to GND and CP3.
Set the probe to X10 and set the oscilloscope at
50 nS/division to display a 100 to 300 nS negative
going pulse.
Apply power to the computer.
While formatting a 5-1/4" diskette, adjust the
PRECMP 1 control (R3) until the pulse width displayed
on the oscilloscope corresponds with the manufacturer's
suggested write precompensation value.
While formatting an 8" diskette, adjust the
PRECMP 2 control (R4) until the pulse width displayed
on the oscilloscope corresponds with the manufacturer's
suggested write precompensation value.
Power down the computer.
Disconnect the oscilloscope probe.
This completes the write precompensation adjustment.
NOTE: All diskettes should be reformatted before being
used.