Instruction manual

Checks and Adjustments
5-22
1720/1721
c. Change the Television Signal Generator’s subcarrier frequency by
--50 Hz for NTSC and PAL-M (--10 Hz for PAL).
d. Connect the voltmeter ground lead to one of the rear-panel ground lugs,
and the active lead to pin 1 of U734.
e. Adjust C235 for a locked display and a voltmeter reading of 0.5 V for
NTSC and PAL-M (1 V for PAL).
f. Change the generator’s subcarrier frequency by +50 Hz for NTSC and
PAL-M (+10 Hz for PAL) and check for a locked display.
g. Return the generator to subcarrier frequency.
7. Adjust Center Dot Overlay and Vector Position
a. Disconnect the Television Signal Generator output from the CH-B
INPUT.
b. Change the 1720/1721 MODE to BOTH.
c. Adjust R355 (Vector Vertical Position) for the best dot overlay.
d. Adjust R653 (Vector Horizontal Position) for the best dot overlay.
e. Change the 1720/1721 MODE to VECTOR.
f. Adjust the 1720/1721 front-panel horizontal and vertical position
controls to center the dot at the graticule center mark.
8. Adjust Phase an d Gain Match
a. Connect the Television Signal Generator color bar output through a 75Ω
feed through termination and dual-input connector to both the C H-A and
CH-B inputs.
b. Set INPUT to BOTH (hold INPUT switch until both the A and B
indicators light).
c. Set the front-panel GAIN CAL to midrange.
d. Adjust C198 (Channel A Input Compensation) and R594 (Gain Match)
for the best gain and phase match of the two vector displays.
9. AdjustXandYGains
a. Set the Function Generator for a 1 kHz sinewave output, and adjust the
output voltage to the desired level, between 2 V and 9 V. (The
1720/1721 is shipped at 2.19 Volts.)