ARMY TM 5-6675-308-34
MARINE CORPS TM 08837A-34/2
high, This point is supplied by a diode from either the
(6) Start removing one at a time, until short is
vehicle power or the backup power. This means that
removed, the power inverter assembly A6,
AUX + 24V will exist if only one of the power sources
28V converter-regulator circuit card assembly
is available. The AUX + 24V is protected from vehicle
A3, + 17V converter-regulator circuit card
assembly Al, + 20V converter-regulator cir-
voltage transients to 50 volts. This protected AUX
+ 24V is sent to the computer power supply on 3J5-5
cuit card assembly A2, and sequence monitor
and is used to drive relay K1. The + 12V is generated
circuit card assembly A5, Monitor standoff
from the AUX + 24V to turn the system on. The + 12V
terminals El and E2 until short disappears.
is used on 28V converter-regulator circuit card assem-
(7) Reinstall all circuit card assemblies except one
bly A3 to power the switching regulator circuits until
which is determined to have caused short and
the + and 14V is available. The + 12V is also used
verify that no other shorts exist.
on the sequence monitor circuit card assembly A5.
(8) Replace suspected malfunctioning circuit card
Perform subroutine no. 4 as follows:
assembly.
(1)
Measure AUX + 24V at relay K1-X2.
(9) If short between standoff terminals El and E2
(2) If AUX + 24V is not present, set BATTERY
still exits' with disconnection of filter circuit
and VEHICLE circuit breakers CB1 and CB2
card assembly A4, disconnect standoff terminal
to OFF.
El and see if short is removed from between
standoff terminals El and E2.
(3) Set PSTS INPUT POWER UUT circuit
breaker to OFF.
(l0) If short remains, replace filter circuit card
assembly A4.
(4)
Set INPUT POWER PSTS circuit breaker to
OFF.
(11) If short is removed, check diode CR5 and the
output filter circuit card assembly A9.
(5) Set O to + 40V input power source to off.
f. PS Troubleshootfng Subroutine No. 3- Relay
(6) Replace battery charger circuit card assembly
Check. This subroutine checks the function of relay K1.
A7.
Relay K1 is the main system on-off relay. It connects the
+ 24V input power from either vehicle or the backup
(7)
Set PSTS INPUT POWER PSTS circuit
battery, or both, to the power bus leading to the
breaker to ON.
regulators and inverters. Coil K1-X2 is connected to the
(8) Set INPUT POWER UUT circuit breaker to
+ 24V power by diodes on the battery charger circuit
ON.
card assembly A7, The other side of coil K1-X1 is
connected to ground to energize the relay by the se-
(9)
Set O to + 40V input power source to on.
quence monitor circuit card assembly A5. Perform
Set BATTERY and VEHICLE circuit breakers
(l0)
subroutine no. 3 as follows:
CB1 and CB2 to ON.
(1) Set BATTERY and VEHICLE circuit breakers
(11) Check for + 12V at sequence monitor circuit
CB1 and CB2 to OFF.
card assembly A5 connector P2-1.
(2) Remove lead from standoff terminal E1 (on
If + 12V is not present, the fault is in one of
(12)
filter circuit card assembly A4).
three assemblies; 28V converter-regulator cir-
(3) Check from lead to ground for O VDC.
cuit card assembly A3, sequence monitor cir-
cuit card assembly A5, or battery charger
(4) Set BATTERY and VEHICLE circuit breakers
circuit card assembly A7.
CB1 and CB2 to ON.
(5) Ground relay K1-XL
Set BATTERY and VEHICLE circuit breakers
(13)
CB1 and CB2 to OFF.
(6) Voltage between lead removed from terminal
El and ground should be +23 to + 29V.
(14)
Set PSTS INPUT POWER UUT circuit
breaker to OFF.
(7) If less than + 23V, check diode CR5 for short.
If not shorted, replace relay K1.
(15)
Set INPUT POWER PSTS circuit breaker to
OFF.
(8) Reinstall lead on standoff terminal El.
(16)
Set O to + 40V input power source to off.
g. PS Troubleshooting Subroutine No. 4 - A UX
+24V and +12V and +12V Check.This subroutine checks the
(17)
Remove 28V converter-regulator circuit card
functioning of the internal voltages AUX +24V and the
assembly A3.
+ 12V. The power supply generates for internal use the
(18)
two voltages called AUX + 24V, and + 12V. The AUX
Set PSTS INPUT POWER PSTS circuit
breaker to ON.
+ 24V starts at A7-J-11 and is called main relay coil
4-122
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