Figure 6-2. Connections for reference supply tests.
fail to meet the requirements, proceed as de-
scribed below. If the readings meet the re-
quirements, proceed to k below.
This test will check the minimum and maxi-
(1) Turn the POWER switch to OFF.
mum output voltage at the output terminals
(2) Rotate the COARSE ADJ. control
of the power supply. Before performing these
extremely counterclockwise.
tests, connect the equipment as described in
(3) Loosen the setscrews in the coupling
assembly of the variac-to-R30 shaft
a. Prepare the dc voltmeter for voltage tests
as described in TM 11-6625-438-10, and set the
(4) Connect the dc voltmeter test leads
VOLTAGE RANGE switch to the 50-volt dc
range.
(5) Set the dc voltmeter VOLTS RANGE
switch to the 50-volt range.
the power supply front panel output termi-
(6) T u r n the power supply POWER
nals.
switch to ON.
Note: Connect the positive voltmeter lead to the
(7) Hold the shaft of resistor R30 in
s t r a p p e d + (red) binding posts, and connect the
place and rotate the COARSE ADJ.
negative voltmeter lead to the - (black) strapped
control until the dc voltmeter reads
binding posts (fig. 2-1).
between 20 and 21 volts dc.
c. Adjust the variac for an output to the
Note: This adjustment will set up the
power supply of 115 volts ac. Use the multi-
minimum dc voltage which the main power
meter to accomplish this adjustment.
supply will always apply to the passing
d. Rotate the COARSE ADJ. control ex-
stages. It is one of the requirements for
tremely clockwise.
obtaining the proper bridge operation of
e. Turn the power supply POWER switch
the reference supply and the main power
to ON.
supply.
f. The dc voltmeter should indicate between
(8) Turn the POWER switch to OFF.
(9) Tighten the setscrew on the shaft
+ 35.7 and 36.3 volts dc.
g. Disconnect the test leads and change the
coupling.
VOLTS RANGE switch of the dc voltmeter
(10) Turn the POWER switch to ON.
from the 50-volt setting to the 0.5-volt setting.
(11) The reading on the dc voltmeter
h. Rotate the COARSE ADJ. control ex-
should remain at 20 to 21 volts dc.
tremely counterclockwise.
(12) If the voltage reading changes out-
i. After connecting the dc meter leads back
side the range of 20 to 21 volts, re-
to the output terminals, the dc voltmeter
p e a t the procedure given in (7)
should indicate between -0.01 to -0.02 volts
through (11) above.
dc.
k. Make minimum voltage to maximum volt-
j. If the readings specified in f and i above
age range final adjustments as follows:
