Heathkit IO-4550 - Page 36

Page 34
9. Adjust Y2 input trimmer capacitor C111-2 (+ 1) for
the correct amount of compensation. If you obtain
proper compensation, disregard the following lettered
steps and proceed to step 10. If you cannot obtain
Proper compensation, perform the following lettered
steps.
A. Adjust Y2 input trimmer capacitor C111-2 (+1)
for the maximum amount of overshoot on the
leading edge of the waveform as shown in Part A
of Figure 21. This adjustment sets the Y2 input
capacitor to minimum capacitance.
B. Adjust the probe trimmer for the proper amount
of compensation.
Cc. Disconnect the probe from the Y2 INPUT
connector and connect it to the Y1 INPUT
connector.
D. Set the indicated front panel controls as follows:
Y1POSITION Center the trace on the screen
Y2POSITION Fully counterclockwise (OFF)
TRIG Y1,+
“E. Adjust the Y1 input trimmer capacitor C111-1
(+1) for the proper amount of compensation.
10. Set the indicated front panel controls as follows:
Y1:
POSITION Center the trace on the screen.
VOLTS/CM 100 mV (or 200 mV or 500 mV
if necessary)
Y2:
POSITION Fully counterclockwise (OFF)
VOLTS/CM 100 mV (or 200 mV or 500 mV
if necessary)
TRIG Y1,+
11. Connect the probe to the Y1 INPUT connector.
Input Compensation
NOTE: Readjust the 1000 Hz square wave amplitude as
necessary throughout the following procedure to increase
the display amplitude.
1. Channel Y1: Perform the following lettered steps
(A-K). Adjust only the controls and trimmer
Capacitors marked Y1 or associated with Channel Y 1.
A. — Adjust the POSITION control to put the trace in
the center of the screen.
B. Adjust trimmer capacitor C108 (+ 10) for the
proper amount of compensation.
C. Turn the VOLTS/CM switch to the 1V position
(or 2V or 5 V if necessary).
D. Adjust trimmer capacitor C105 (+ 100) for the
proper amount of compensation.
E. Turn the VOLTS/CM switch to the 10V position
(or 20V if necessary).
F. Adjust trimmer capacitor C102 (+ 1000) for the
proper amount of compensation. Examine this
display carefully as it may be quite small.
G. Turn the POSITION control fully
counterclockwise (OFF) and decrease the
amplitude of the 1000 Hz square wave signal.
H. Turn the TRIG switch to Y2, +.
Disconnect the probe from the Y1 INPUT connector and
connect it to the Y2 INPUT connector.
Channel Y2: Perform the previous lettered steps (A-G).
Adjust only the controls and trimmer capacitors marked Y2
or associated with Channel Y2.
Disconnect the square wave signal from the Oscilloscope.
Set the indicated front panel controls as follows:
Y1:
INPUT switch GND
POSITION Center the trace on the screen
Y2:
INPUT switch GND
POSITION Fully counterclockwise (OFF)
Proceed to ‘Touch-Up Adjustments.”
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