Table 4-6. Performance and Troubleshooting Test for the -48 Vdc Power Supply SM-F-935778-Continued

TM 11-5895-1123-34

Step

Test setup instructions

Normal indication

If indication is abnormal

q. On the test fixture, momentarily turn the LINE

Minimum -40 vdc, that is,

Replace A2.

switch to the OFF position and then back to ON

-41, -42, are acceptable.

and observe the reading on the digital multimeter.

r. On the UUT, adjust the VOLTAGE ADJUST for

-48.5 .1 vdc

Replace A2.

- 48.5 + .1 vdc as indicated on the digital multime-

ter.

Voltage Sensor Tests:

a. On the UUT adjust the VOLTAGE ADJUST for a

-44 +.1 vdc

Replace A1.

-44 .1 vdc as indicated on the digital voltmeter.

b. On the test fixture, remove the digital multimeter

-44 .2 vdc

Replace A3.

lead from J2M and connect it to J2A and observe

the reading on the digital multimeter.

c. On the test fixture, remove the digital multimeter

-44 +.2 vdc

Replace A3.

lead from J2A and connect to J2E and observe the

reading on the digital multimeter.

d On the test fixture, remove the digital multimeter

Less than - 1 vdc

Replace A3.

lead from J2E and connect it to J2B and observe

the reading on the digital multimeter.

e. On the UUT, slowly adjust theVOLTAGE ADJUST

-45 to -46 vdc

Replace A3.

in a clockwise direction to the point where a volt-

age greater than -1 volt appears on the digital

multimeter and read the voltage.

NOTE

Step 2f below is used to adjust the UUT to its final dc

setting.

f On the UUT, adjust the VOLTAGE ADJUST for a

-48 + .1 vdc indication on the digital multimeter

and tighten the lockout on the adjustment screw.

LineS.oad Regulation Test:

a. Remove the digital multimeter leads from the test

fixture and set the controls on the digital multime

ter as follows:

FUNCTION

ACV

RANGE

200

b. On the test fixture, connect the leads from the digital

multimeter across J1A and J1C and adjust the

variac for an indication of 127 t 1 vac as indicated

on the digital multimeter.

c. Remove the digital multimeter leads from the test

fixture and set the controls on the digital multime

ter as follows:

FUNCTION

DCV

RANGE

200

d. On the test fixture, connect the positive lead from the

-49 vdc maximum; that is,

Replace A1.

digital multimeter to J2M and the ground lead to

-47, -48, etc., is acceptable.

J2K and observe the indication on the digital mul-

timeter.

e. Remove the digital multimeter leads from the test

fixture and set the controls on the digital multime-

ter as follows:

FUNCTION

ACV

RANGE

200

f On the test fixture connect the leads from the digital

multimeter across J1A and JIC and adjust the

variac for an indication of 103 1 vac as indicated

on the digital multimeter.

g. Remove the digital multimeter leads from the test

fixture and set the controls on the digital multime

ter as follows:

FUNCTIONDCV

RANGE200

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