Checks and Adjustments
1705A Spectrum Monitor 5-21
b. Exit the DAC test patternby first pressing the INPUT button to display
the TEST menu.
c. Press eitherS PAN/DIVbutton to move the cursor to EXIT, then press
the INPUT button twice to returnto a normal display.
A3 MAIN BOARD
(Referto Figure 5-7 for adjustment locations)
5. AdjustOn-Board Regulated PowerSupplies
a. Connect the voltmeterground lead to the rear-panel LNB POWER
switch ground lug, and the activelead to the --11.8V test point (W8).
SeeFigure5-7.
b. ADJUST -- R 99 ( --1 1. 8 V AD J) f or -- 11 .8 V ( --1 1. 78 t o --1 1. 82 V ).
c. Connect the voltmeter activelead to the +11.8 V test point (W9). See
Figure 5-7.
d. ADJUST --R111 ( +11.8 V ADJ ) for +11.8 V (+11.7 8 to +11.8 2 V).
6. Adjust Horizontal Gain
a. Connect a shorting strapbetween W11 and W12. See Figure 5-9.
W11
W12
SHORTING
STRAP
Figure5 -9: Location of the shorting strap used when adjusting sweep length
b. ADJUST -- R168 (HORIZ GAIN) for a sweeplength of 10 major
Divisions. Use the --60horizontal graticule line as the reference.
c. Remove the shorting strap.