TM9-4935-481-14-1
Table 3-19. LET Performance Test-Continued
Table 3-19. LET Performance Test-Continued
STEP
UNIT
PROCEDURE
CORRECTIVE ACTION
STEP
UNIT
PROCEDURE
CORRECTIVE ACTION
50
LET
Raise the breech block assembly fully until it clicks and allow
62
DMM
Observe a reading of > 18.0 Vdc. If voltage is too low reinstall,
it to remain in the upright position.
in the proper direction, one of the batteries reversed in step 60.
51
PPE
Momentarily actuate TEST START switch.
Re-verify the DMM reading.
52
OSC
Hand hold the LET solenoid armature, (Refer to TM 9-6920-480-34)
63
PPE
Momentarily actuate TEST START switch.
TPS
64
TPS
Momentarily actuate the TRIGGER switch.
and momentarily actuate the TRIGGER switch and observe the
65
DMM
Observe an OPEN (meter drifts).
66
UUT
Raise fully upright and then lower and lock the breech block
assembly.
67
MCP
SELECTOR A switch to D21.
68
DMM
Observe a reading of > 18.0 Vdc.
69
PPE
Momentarily actuate TEST START switch.
70
TPS
Momentarily actuate TRIGGER switch.
71
DMM
Observe an open reading (meter drifts).
72
MCP
SELECTOR A switch to E3.
53
LET
Lower and lock the breech block assembly.
73
DMM
Observe a reading of < 0.5000 Vdc.
54
DMM
Observe a reading and display of > 24.0 Vdc.
74
PPE
Momentarily actuate TEST START switch.
55
OSC
Observe the display goes to < 1.85 Vdc, 675 + 100 msec after
75
TPS
Momentarily actuate TRIGGER switch and observe no indication of
TPS
OSC
the TRIGGER switch is momentarily actuated.
the LET firing.
56
DMM
Observe an open reading (meter drifts).
76
LET
Raise fully upright and then lower and lock the breech block
57
LET
Raise fully upright and then lower and lock the breech block
assembly.
assembly.
77
DMM
Observe a reading of +15.00 to +18.00 Vdc.
58
UUT
Remove the cover over either of the battery tubes.
78
MCP
SELECTOR A switch to E4.
59
UUT
Remove 3 batteries.
79
DMM
Observe a reading and display of < 0.5000 Vdc.
60
UUT
Reinstall 2 batteries in the reverse position (Reverse polarity).
OSC
61
UUT
Reinstall the final battery in the proper direction per the
polarity diagram in the tube. Tighten down the battery holding
bolt.
3-321