TM 55-4920-428-13
g. (See fig. 4-2.) On circuit board PS2, adjust variable resistor R10 until the multimeter indicates
28.0 volts dc.
h. Set the power switch to OFF.
i. Disconnect the multimeter and the power cable from the autotransformer.
j. Perform the power supply and DVM tests. (Ref para 4-40.)
k Install the panel. (Ref para 4-41.)
l. Perform the final test. (Ref para 4-42.)
4-39. Adjustment of DVM.
The DVM is not adjusted at AVIM level.
4-40. Power Supply and DVM Preliminary Test.
Test the power supplies and the digital voltmeter whenever their performance is suspect and prior to
final test. (Ref para 4-42.) Perform the test procedure in the sequence in which it is presented.
a. Test Equipment Required. The following test equipment is required.
EQUIPMENT
SPECIFICATION
Multimeter
AC: 50mV to 150V, 0.5%
DC: 10mV to 50V, 0.1%
Frequency Counter
0.5 Hz to 1 KHz, 0.1%
b. Preliminary Procedures.
(1) Remove the panel. (Ref para 4-18.)
(2) (See fig. 6-3.) Loosen two thumbscrews securing the cover to terminal board TB5 (26).
Remove the cover.
(3) Set the power switch to OFF.
(4) Connect power cable 145GS278-4 to POWER receptacle and 115-volt 60 Hz source.
c. Input Voltage Test.
(1)
TB5-3.
(2)
(3)
(4)
(5)
d. Dc
(1)
(2)
(3)
(4)
Set the multimeter to measure ac volts. Connect the multimeter to terminals TB5-1 (line) and
Set the power switch to ON.
The multimeter shall indicate 112.5 to 117.5 volts ac.
Set the power switch to OFF. Disconnect the multimeter.
Install the cover on terminal board TB5.
Voltage Tests.
Set the multimeter to measure dc volts.
On terminal board TB4 (22), connect the negative multimeter probe to terminal TB4-1.
Set the power switch to ON.
In turn, connect the positive multimeter probe to the following terminals. The multimeter in-
dications shall be as specified. When measuring at terminal TB4-9, record the multimeter indication
for use during the DVM test.
4-14
