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23. Analog-To-Digital Converter Adjustments
1. Adjust
A3A8R5
GAIN for a square wave displayed on the
oscilloscope. The square wave should be approximately 4
V,,.
See Figure 3-86 for location of adjustment.
Alternate Procedure
4. Procedure without using Low-Noise DC Supply:
a. Press
QNSTR
PRESET].
b. Key in TRACE A
[BLANK]
and SWEEP (SINGLE).
c. Disconnect cable 0 (black) from sweep ramp input
A3A8Jl.
d. Short
A3A8TP4
to
A3A8TP5
or connect SMB snap-on short to
A3A8Jl.
e. Connect DVM to
A3A8TPll
and ground to
A3A8TP4.
Set DVM
for V ac.
f. Adjust
A3A8R6
OFFS until the level at
A3A8TPll
is at a
maximum ac voltage as indicated by the DVM (approximately
2.0 V ac). See Figure 3-86 for location of adjustment.
g. Remove short from A3A8TP4 and
A3A8TP5.
Reconnect cable 0
(black) to A3A8J 1.
h. Press ~NSTR PRESET].
i. Connect DVM to
A3A8TP5
and ground to
A3A8TP4.
Set DVM
for V dc.
j. Press SWEEP
C-1.
Note DVM reading at end of the sweep.
The voltage will begin to drift immediately after the sweep
ends. Therefore, the first indication after the sweep ends is the
valid indication. It may be helpful to press
[SINGLE)
several times
to ensure a valid indication at the end of the sweep.
k. If DVM indication is
+
10.020
f0.005
V dc at the end of the
sweep, no further adjustment is necessary. Otherwise, adjust
A3A8R5
GAIN and repeat step j until the voltage at the end of
the sweep is + 10.020
fO.005
V dc.
Adjustments 3-141