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Section V
ADJUSTMENT PROCEDURES
Model 3476A
5-19. ADJUSTMENT PROCEDURE.
5-20. Refer to Figure 5-5 for the following adjustments.
NOTE
The resistors used in the adjustment procedure
must be floating.
5-21. Power Supply Adjustment.
a. Connect a I kilohm resistor to the V/SZ and COM
terminals. Set the FUNCTION to
kn
and ensure that the
HOLD pushbutton is out.
b. Connect a DC Digital Voltmeter between + 6 V test
point and ground.
c.
Adjust R47 for 5.94 to 6.06 V dc on the Digital
Voltmeter.
d.
If it is not possible to adjust within this limit, change
the adjustment range of R47 by replacing or removing
JMPR 7. Removing JMPR 7 will allow a more positive ad-
justment of TP + 6.
5-22. Substrate Adjustment.
a.
A 1 kilohni resistor should still be connected between
the V/S2 and COM terminals. Connect a jumper between
the + 1 test point and TP G.
b. Ensure that the
Multirneter downranges to the
1.1 la2 range and adjust R42 for an indication between
.078 and .082 on the display. If these limits cannot be ob-
tained, an indication of 000 to 078 is acceptable if R42 is
fully counterclockwise.
5-23. Input Amplifier Zero Adjustment.
5-24. The following adjustment requires that the Multi-
meter be set to a DC V function, 110 V range with no input
applied. Since the Multimeter is autoranging, it is necessary
to force it to the 110 V range and then use the HOLD func-
tion to keep it there.
a.
Remove the jumper connected between + 1 and TP G
in the previous step.
b. Set the function to kS2 and connect a 300 kilohm
resistor between the
sztv
and COM terminals. When the
Multimeter autoranges to the 1.1 megohm range, push the
HOLD pushbutton in. This is equivalent to the 110 V
range.
c. Change the Multimeter FUNCTION to DC V. Re-
move the 300 kilohm resistor from the input and replace it
with a short.
d. Connect a jumper between Ul pin 12 and analog
ground (TP <7 ).
e. Connect a DC Digital Voltmeter to Test Point A.
Adjust R38 for an indication between - 1 and + 1 mV de on
the Digital Voltmeter.
NOTE
The following adjustment requires the same test
setup. Do not change the setup or FUNCTION
settings.
5-25. Integrator Amplifier Zero Adjustment.
5-26. This test requires the same test setup and functions
as the previous adjustment.
a.
Adjust R10 for a display equal to - 1000 times the
value at Test Point A in the previous adjustment, ± 1 count.
Example:
Voltage at A = . 2 mV
.2 mV x(- 1000) = - 00.2 V Display
b.
If R10 does not have sufficient range for this adjust-
ment, remove JMPR 6 and repeat Step a. If JMPR 6 has
already been removed, it may be necessary to replace it.
NOTE
If JMPR 6 is open, a more positive voltage can
be obtained at TPA by adjusting the Integrator
Offset Adj. (RIO).
5-27. + DC Volt Gain Adjustment.
a.
Remove the DC Digital Voltmeter and jumper be-
tween Ul pin 12 and analog ground. Release the HOLD
function, and remove the short from the input.
b. Set the Multimeter FUNCTION to DC V. Apply an
input of + 1.000 V dc. The Multimeter should autorange to
the 1.1 V range for this adjustment.
Ai
c.
Adjust R47 for a display of 1.000. If R47 does not
have sufficient range, change the adjustment range of R47
by replacing or removing JMPR 7. Removing JMPR 7 will
allow a more positive adjustment of TP + 6.
5-28. — DC Volt Gain Adjustment.
a.
Leave the Multimeter FUNCTION set to the DC V
and HOLD function out. Change the input from + 1.000 to
- 1.000.
b.
Adjust R14 for a Multimeter display of - 1.000 V dc.
NOTE
Leave the - 1.00 volt source connected for the
following adjustment.
5-29. Clock Frequency Adjustment.
a.
Set the Multimeter FUNCTION to DC V, HOLD
Function out and - 1.000 volts connected to the input.
5-6
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