TM 9-4935-481-14-1 C3
Table 3-19. LET Performance Test-Continued
Table 3-19. LET Performance Test-Continued
STEP
UNIT
PROCEDURE
CORRECTIVE ACTION
STEP
UNIT
PROCEDURE
CORRECTIVE ACTION
23
MCP
Connect 1W20-P1 to J12 and 1W20-P2 to the BNC tee at the oscillo-
scope A INPUT.
NOTE
24
MCP
Connect a cable from J13 to the oscilloscope MAIN, EXT INPUT.
Any corrective action required during the remainder
25
CT
Adjust DISPLAY control fully cw (to HOLD).
of this procedure due to incorrect readings will be
26
CT
A INPUT switch to pos.
performed by troubleshooting utilizing the LET
schematic in TM 9-1425-484-24 and the DMS-D LET
27
CT
B INPUT switch to neg.
28
CT
FUNCTION switch to TIME A -+ B.
29
CT
FREQ/TIME/MULT switch to 101.
39
LET
Raise fully upright and then lower and lock the breech block
30
OSC
TIME/DIV switch to 2 MSEC.
.
assembly
31
OSC
INT/EXT pushbutton switch to EXT.
40
MCP
SELECTOR A switch to D22.
32
OSC
AUTO/NORM pushbutton switch to NORM and set up scope for EXT.
41
DMM
Observe a reading of > 24.0 Vdc.
TRIGGER.
33
OSC
CHANNEL A INPUT VOLTS/DIV switch to 1.
If less replace all batteries in the
34
OSC
CHANNEL A INPUT coupling switch to DC.
LET.
42
MCP
SELECTOR A switch to D20.
35
PPE
Momentarily actuate TEST START switch.
36
CT
Momentarily depress RESET pushbutton.
43
PPE
Momentarily actuate TEST START switch.
44
PPE
Momentarily actuate the TRIGGER switch and observe a +2.0 + 0.1
37
TPS
Momentarily actuate TRIGGER switch and observe a +2.0 0.1
OSC
OSC
.
Vdc pulse
Vdc pulse.
45
MCP
SELECTOR A switch to D22.
Ensure cabling is correct and review
46
DMM
Observe an open reading (meter drifts).
switch settings. Perform DMS-D
Clean trainer lAW TM 9-6920-480-34.
performance test/trigger safe test.
38
CT
Observe a reading of 9.50 to 10.50 msec.
47
OSC
TIME/DIV switch to .2 SEC.
Ensure cabling is correct and review
48
OSC
CHANNEL A INPUT VOLTS/DIV switch to 10.
switch settings. Perform DMS-D
49
OSC
Adjust CHANNEL A POSITION control to the vertical center line.
performance test/trigger safe test.
3-320