
22. Analog-To-Digital Converter
Adjustments
A3A8
ANALOG-TO-DIGITAL CONVERTER
(Beneath Cover)
Alternate Procedure 4.
Procedure without using Low-Noise DC Supply:
TPll
G::N
TP4 TP5
A3A8
GA,,,
Figure 3-101.
Location of Analog-lb-Digital Converter Adjustments
a.
b.
C.
d.
e.
f.
g.
h.
i.
i
k.
Press
(2-22].
Key in TRACE A
ljZZZ]
and SWEEP
[w).
Disconnect cable 0 (black) from sweep ramp input A3ASJl.
Short
A3ASTP4
to
A3ASTP5
or connect SMB snap-on short to
A3ASJl.
Connect DVM to
A3ASTPll
and ground to
A3ASTP4.
Set DVM
for V ac.
Adjust
A3ASR6
OFFS until the level at A3ASTPll is at a
maximum ac voltage as indicated by the DVM (approximately
2.0 V ac). See Figure 3-101 for location of adjustment.
Remove short from
A3ASTP4
and
A3ASTP5.
Reconnect cable 0
(black) to A3ASJl.
Press
[O-2.5].
Connect DVM to
A3ASTP5
and ground to
A3ASTP4.
Set DVM
for V dc.
Press SWEEP
Cm].
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
Cm)
several times
to ensure a valid indication at the end of the sweep.
If DVM indication is + 10.020
f0.005
V dc at the end of the
sweep, no further adjustment is necessary. Otherwise, adjust
A3ASR5
GAIN and repeat step until the voltage at the end of
the sweep is + 10.020
f0.005
V dc.
3-208
Adjustments
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