TM 9-4120-402-14
5-8. LOGIC BOX ASSEMBLY (LGC1).
This task covers: Test
INITIAL SETUP
Tools
Equipment Conditions:
Refrigeration Unit Service Tool Kit
CAUTION
Logic Box Test Fixture
Use disconnect switch (NOT POWER
CABLE) to disconnect power to unit.
Damage to cable connector pins will
Materials/Parts
result if cable is used.
Logic Box Assembly
Disconnect power from power source.
Test.
NOTE
If a complete test fixture is unavailable, see appendix F, figure F-51 for a schematic and parts list
to fabricate one.
(1) If a complete test fixture is being used, connect it to a standard convenience outlet and be sure the POWER
switch is in the OFF position. (See figure 5-1.) If a test fixture was fabricated per schematic (appendix F,
figure F-51), connect the power supply to
appropriate power source and adjust output to
120.5 volts dc. Be
sure it is turned off and connected to the test fixture where indicated.
(2) Connect a multimeter set to measure dc voltage to the test fixture TEST POINT (positive lead to TP1 and
negative lead to TP2). Connect P1, P2, and P3 to J1, J2, and J3 respectively on the logic box assembly being
tested.
NOTE
If the logic box assembly fails any of the following tests, the entire assembly must be replaced.
Do not continue testing beyond a failure point.
5-13