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Adjustment Procedures
5–40
1780R-Series Service Manual
d. Use the HORIZ POS control to position the center of the vertical sync to
the mid-screen graticule mark.
e. Set the WFM HORIZONTAL-MAGNIFIER to OFF.
f. Adjust H Mag Reg (A2R344) to center the vertical sync on the screen.
g. Disconnect the Color Bar signal from the CH A INPUT.
NOTE. If A2R344 was adjusted, go to step 9. Readjust WFM Readout H Center
(A2R170) and WFM Readout Gain (A2R167).
34. Adjust Slow Sweep Trigger Level
a. Connect a 50% APL signal from the television test signal generator,
through a 75 W feed-through terminator, to the 1780R-Series CH A
INPUT.
b. Select REF-INT and WFM HORIZONTAL-TWO-LINE sweep. Check
that INPUT-CH A is selected.
c. Connect a test oscilloscope 10X probe to pin 2 of A2U458.
d. Set the test oscilloscope controls to establish a ground reference.
e. Set the test oscilloscope controls to 20 mV/ Div, DC-coupled, and
10 ms/Div. Monitor the voltage level at pin 2 of A2U458.
f. Adjust Slow Sweep Trig Level (A2R761) for 0 V average on the test
oscilloscope CRT.
g. Remove the 10X probe from the test point. Disconnect the 50% APL
signal from the CH A INPUT.
35. Adjust VCO Lockup
a. Connect the television test signal generator Color Bar signal through a
75 W feed-through terminator to the CH A INPUT. Check that the
generator Black Burst signal is connected to the EXT REF connector and
terminated into 75 W.
b. Select REF-EXT. Check that INPUT-CH A and WFM HORIZONTAL-
TWO-LINE sweep are selected.
c. Connect the Digital Multimeter (DMM) Volts lead to A7TP286 and the
common (or Low) lead to chassis ground. A7 is the Oscillator board. See
Fig. 5–16.