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070-3783-01 492/492P Service Vol. 1 9-2-83 Rev
j. On the sweep oscillator, change to the automatic internal sweep
(Marker Sweep) and set the sweep time for 100 s/sweep (its slowest
sweep ).
k. Activate VIEW A and VIEW B, then select a sweep time on the
492/492 so the stored display is solid (no breaks in the digitized
display, Fig. 3-37A).
1. Activate MAX HOLD. Trace and record the response of Band 4.
Activate SAVE A.
m. Deactivate VIEW A and MAX' HOLD (SAVE A and VIEW B are still
active).
n. Activate 10 dE/DIV and note the baseline. Activate NARROW Video
Filter, and adjust the REF LEVEL so the baseline moves to the top of
the screen.
o. Press 2 dE/DIV and VIEW A, then adjust the REF LEVEL so the
SAVE A display and the baseline are at center screen.
p.
Unplug P2060 (Fig. 3-36) and move it from the Normal to Invert
mode position (one pin to the left). Replace Leveler Disable plug P3035.
q. Start with R1061 and adjust the leveling potentiometers sequen
tially, from R1061 through R1013, so the contour of the baseline is an
average of the SAVE A display. In the process, use Horiz adjust R1069
(Fig. 3-36) to shift the baseline to the right or left so the baseline
aligns with the average contour of the SAVE A display.
r. Replace F'2060 to the Normal mode position (one pin to the right).
The baseline will now be ISO degrees or the inverse of its previous
position.
•s. Deactivate and then activate VIEW A, VIEW B, SAVE A, and MAX HOLD.
Retrace and check new response. Response should appear flat (Fig. 3-37B).
t Disconnect and remove the signal to the RF INPUT from the test
equipment.
u Compensation adjustment R1065 is set at the factory and usually
does not require adjustment. Pull Leveler Disable plug P3035, then
replace it. If the baseline remains straight or breaks up after the
plug is replaced, compensation is required. The adjustment procedure
is as follows.
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