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Adjustment Procedures
5–24
1780R-Series Service Manual
remain lit but not the A-B1 selection.) The display should become a
nearly flat trace and the left CRT should display the messages:
"COMMON MODE B1"
"TOUCH HERE TO EXIT"
g. If these messages are not displayed, repeat part f. of this step. Move
quickly from touching the screen to selecting the A-B1 INPUT;
otherwise, the messages may not appear.
h. Adjust LF CMR (A2R1033) for minimum amplitude.
i. Touch the message “TOUCH HERE TO EXIT.” Press the CONFIGURE
button to exit the menu. Set the WAVEFORM GAIN-X5 to Off.
j. Disconnect the Color Bar signal and terminator from the CH B1 INPUT
connectors.
16. Adjust CH B1 Input Gain
a. Connect the VAC output to one side of the 1780R-Series CH B1 INPUT.
Do not terminate. Check that a Black Burst signal is applied to the EXT
REF Connector.
b. Check that the VAC is set for 999.9 mV output amplitude. Check that
the +Lum button is pressed in and the Lum/Sync button is out. Check
that the correct television standard (NTSC, PAL, or PAL-M) is selected.
c. Check that CH B1 INPUT is selected.
d. Select 1780R-Series RIGHT DISPLAY–WFM+CAL mode. Press the
CONFIGURE button to On. Check that COUPLING-DC and DC
RESTORER-OFF are selected.
e. Position the meeting point of the upper and lower (stacked) calibrator
signals to the graticule baseline (0 IRE for NTSC; 0.3 V for PAL) on the
Waveform CRT.
f. Set the WAVEFORM GAIN-X5 to On.
g. Adjust Gain B1 (A8R347) so that the bottom trace of the upper level
calibrator signal overlays the top trace of the lower level calibrator signal
as displayed on the Waveform CRT. (A8 is the Input & BNC board. See
Figure 5–13.)
h. Select the RIGHT DISPLAY-WFM mode and set the CONFIGURE
button to Off.
i. Leave the DC RESTORER set to OFF.