Install guide

ARMY TM 5-6675-308-34
MARINE CORPS TM 08837A-34/2
Table 4-20.
Computer Power Supply Testing and Troubleshooting - Continued
Malfunction
Test procedure
Normal indication
indication/corrective action
2.
2a.
2b.
2c.
2d.
2e.
2f.
2g.
2h.
COMPUTER POWER
SUPPLY TEST.
Set switches as follows:
Switch
Setting
COMP PS
OFF
INPUT
POWER
PSTS
OFF
INPUT
POWER
UUT
OFF
MODE
OVERLOAD
FUNCTION
COMP PS
+ 5V
REFERENCE
AMB TEMP
V LAMP
0 VDC
SELF TEST
OFF
Turn on external +28V power
source
Turn on external 0 to +40V
power source and adjust to 0V.
Set current limit to 10 amps
Set INPUT POWER PSTS cir-
cuit breaker to ON
Press POWER SUPPLY TEST
SET ON switch-indicator. Set
MODE switch to NO LOAD.
Set INPUT POWER UUT cir-
cuit breaker to ON
Set COMPT PS switch to ON.
Gradually increase external 0
to +40V power source to +24
(±0.5)V. Measure voltage at
COMPUTER POWER SUP-
PLY PWR IN and PWR RTN
test jacks
Set COMP PS switch to OFF,
then to ON
PSTS fan comes on
POWER SUPPLY TEST SET ON
switch-indicator goes on
Current drawn from 0 to +40V ex-
ternal power source is less than 7
amps and COMP PS ON indicator
lights
COMPS PS ON indicator goes off,
then lights
If a short is indicated, exchange 5V
power
supply circuit card
assembly A1, then 15V power
supply circuit card assembly A2,
then wiring harness A3
If indicator light does not go off
when COMP PS switch is set to
OFF, replace 15V power supply
circuit card assembly A2
If indicator does not stay on when
COMP PS switch is set to ON, try
replacing 5V power supply circuit
card assembly A1, or 15V power
supply circuit card. assembly A2,
or wiring harness A3
Change 2 4-127