TM 11-6625-444-14-1
(
(5) Repeat step (4) with negative input
RATIO FULL SCALE control, if required, to
voltages. The readout must be the same as for
obtain required readout.
positive inputs, except that the polarity in-
dication will be negative (-).
(6) Apply zero volts to the INPUT terminals
and depress the AUTO RANGE switch. The
digital readout shall be 00.0000 .0001.
(7) Apply +1000.00 volts dc to the INPUT
range
shall
terminals.
The
automatically and the digital readout shall be
+1000.00 .10.
c. Ratio Accuracy Checks. Connect equipment
as shown in figure 6-25 and set the controls as
follows:
FUNCTION
VDC, FILT, RATIO
10
RANGE
SAMPLE RATE
Full CW
RATIO FULL SCALE
Midposition
(1) Set dc voltage calibrator output to
5. 0000V, observing digital readout is +100.000%
0.050.
(2) Rotate RATIO FULL SCALE control for
a digital readout of +100.000 .001.
(3) Disconnect dc voltage calibrator from the
IN PUT terminals and then connect a shorting
6-17. Alignment
jumper between the INPUT terminals.
( 4 ) Verify that the digital readout is
a. General. The voltmeter shall be aligned
00.0000%. The last digit may flash producing a
every six months or whenever repairs have been
digital readout of 00.0000/1.
made to its internal circuitry. Adjustment and
(5) Reconnect the dc voltage calibrator to
test point locations are shown in figure 6-2. They
the INPUT terminals, except reverse polarity.
are also labeled on the top guard cover. Align-
( 6 ) Verify that the digital readout is
ment should only be attempted after completing
+100.000% 0.001. A d j u s t RATIO FULL
the performance tests in paragraph 6-16. Results
SCALE control, if required, to obtain required
of the performance tests can be used to determine
readout.
if the voltmeter is operational and only requires
minor adjustment (alignment) or that repair
NOTE
(troubleshooting) is necessary.
Ratio of two negative signals is positive.
(7) Connect equipment as shown in figure 6-
b. Equipment Setup. Prior to voltmeter
alignment, p e r f o r m t h e f o l l o w i n g s e t u p
(8) Set dc voltage calibrator output to
procedure:
50.000V, observing that the digital readout is
(1) Unlock the top dust cover fasteners.
+11.9999%..
Leave the dust cover in place.
(9) Select 100V range, observing that the
(2) Set the 115/230 switch on the rear panel
digital readout is 100.00% 0.001. Adjust
to the 115 position.
