TM 11-6625-444-14-2
(7) Adjust A9-R22 for a display readout of
+100.000.
shown in figure 6-21.
(8) Increase the dial-a-volt output to +10V
(3) Select the sinewave output from the
and observe the display readout.
of 60 Hz and a level of 20 V PP as measured
by the oscilloscope (A6).
(9) If readout increases (i.e. +100.100),
adjust A9-R22 for a readout negative by the
same amount (i.e. +99.900).
(4) Remove the top cover of the guard
cage and connect the oscilloscope to A9-U1.
pin 6 on the voltmeter. (Refer to figure 6-22 for
(10) Adjust A9-R10 to bring the display
test point locations.)
readout back to +100.000.
(11) If readout decreases (i.e. +99.900),
ms/div, vertical sensitivity to 5 mV/div and se-
a d j u s t A9-R22 for a readout positive by the
lect ac coupling. Set the probe switch to the Xl
same amount (i.e. +100.100).
position.
(12) Adjust A9-R10 to restore the display
readout to +100.000.
(6) Adjust trimmers A9-C4 and A9-C7 to
reduce the amplitude to less than 20 mV P-P as
displayed on the oscilloscope.
(13) Reduce the dial-a-volt output to +1
The display should still indicate +100.000
If it does not, repeat steps (8)
(7) Disconnect all equipment connections
(+000.010).
from the voltmeter.
through (13).
(14) Disconnect the dial-a-volt.
c. 100 V Full Range (A9-R10)/100 Vdc Com-
mon Mode (A9-R22)
d. 1 V Down Range Adjustment (A9-R18)
(1) Connect the equipment as shown in
(1) Check that the RATlO FULL RANGE
control is still set at its mechanical center of re-
tation.
(2) Select the 20 V range and DC/DC RA-
TIO function on the voltmeter.
(2) Select the 200 V range and DC/DC
RATIO function on the voltmeter.
(3) Apply a +10.00 Vdc signal from the dc
voltage calibrator simultaneously to the volt-
(3) With the equipment connected as
meter HI/LO INPUT (front) terminals and V/LO
shown in figure 6-20, apply a +100,00 Vdc sig-
EXTERNAL REFERENCE terminals.
nal from the dc voltage calibrator simultaneously
to the voltmeter HI/LO INPUT (front) terminals
and V/LO EXTERNAL REFERENCE terminals.
(4) Adjust the front panel RATlO FULL
RANGE control for a reading of +100.000.
(4) Set the dial-a-volt to +1 mV.
(5) Reduce the signal from the dc voltage
calibrator to +1.00 Vdc. If the display reading
(5) Adjust SAMPLE RATE control for ap-
changes, adjust A9-R18 to restore it to an aver-
proximately one display readout every second;
age reading of + 100.000.
(6) Adjust A9-R10 to achieve a reading
half-way between the initial readout observed
(6) Repeat steps (3) through (5) until there
is no change between the display reading for
and +100.000.
6-41
