HP 8560A, Service Manual

Page: 49 / 450

2. Display Adjustment
Procedure
1. Set the analyzer’s switch off. Remove the analyzer’s cover and fold out the A2
Controller and A3 Interface assemblies as illustrated in Figure 2-2. Connect the CAL
OUTPUT to the INPUT. Adjustment locations are shown on the CRT neck for Al7
adjustments and in Figure 2-4 for the A2 adjustments.
Preliminary Adjustments
2. Set X GAIN, Y GAIN, DDD, ASTIG, DGTL
X GAIN, DGTL Y GAIN, STOP BLANK, and START
BLANK to midrange. Also set the rear-panel X POSN, Y POSN, and TRACE ALIGN to
midrange.
3. Set Z FOCUS, X FOCUS, and CUTOFF fully counterclockwise.
4. Set Z GAIN fully clockwise.
5. Turn the analyzer on and allow it to warm up for at least 3 minutes. Adjust
CUTOFF until the display is visible and COARSE FOCUS for best possible
focus.
Cutoff Adjustment
Press
STORE INTENSITY, MORE of 2,
FOCUS STORE FOCUS GRAT OFF.
Adjust CUTOFF until the
line between the bottom of trace A and the annunciators at the bottom of the display just
disappears.
Deflection Adjustments
Press CRAT ON, MORE 2 of 2, STORE
MORE
of 2 , and CRT ADJ
PATTERN
. Fold up the A3 Interface assembly.
8. Refer to Figure 2-3 for locating the lines used for adjusting DGTL X GAIN and DGTL Y
GAIN. Each of these lines is actually two lines adjusted for coincidence. The two lines will
form an “X” if they are not adjusted properly.
9. Adjust DGTL X GAIN until the two vertical lines near the left edge of the
display appear to be one single line.
10. Adjust DGTL Y GAIN until the two horizontal lines near the top edge of the
display appear to be one single line.
11. Adjust STOP BLANK and START BLANK for the sharpest corners of
the outer box in the test pattern. The intensity of the corners should be the same as the
middle of the lines between the corners.
12. Adjust the rear-panel TRACE ALIGN until the leftmost line of the test pattern is parallel
with the CRT bezel. See Figure 2-3.
13. Adjust the rear-panel X POSN and X GAIN until the leftmost characters
and the labels appear just inside the left and right edges of the CRT bezel.
Adjustment Procedures 2-15