Zenith H-100 Service Manual page 74

5-158
FREQUENCY COUNTER METHOD
Allow a fifteen minute warm-up of the board with the
top cover of the computer in place.
Remove the top cover of the computer.
Connect the common test lead of the multimeter to
the GND test point at the upper left side of the
controller board. Refer to the H-207 Controls and
Jumper Locations pictorial.
Connect the positive test lead to the CP2 test point.
Adjust the BIAS control (R2) until the multimeter display
shows +1.40 VDC (+.05 volts). Switch the multimeter
to lower ranges to perform this adjustment accurately.
Disconnect the multimeter.
Connect the common lead of the frequency counter to the
GND test point.
Connect the test probe of the frequency counter to the
CP1 test point.
Adjust the FREQ control (R1) until the frequency counter
display shows 4.000 MHz.
Disconnect the frequency counter.
The adjustments to the Data Separator are now complete.
Proceed to WRITE PRECOMPENSATION ADJUSTMENTS.