TM 1-1520-238-T-5
Change 4
8–97
8–31.
PILOT ENG OIL, TGT, TORQUE, FUEL QUANTITY, ENG–RTR RPM%, AND NG RPM%
8–31
VERTICAL SCALE INDICATORS – DO NOT DIM (MANUAL DIM)
Tools:
Nomenclature
Part Number
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Multimeter, Digital
AN/PSM-45
Personnel Required:
68X
Armament/Electrical Systems Repairer (2)
References:
TM 1-1520-238-23
WARNING
Turn off power before detaching or
attaching wires and connectors. High
current 28 VDC or 115 VAC is present.
Failure to do so could result in death or
serious injury.
1. Detach P787. Check pilot dim/test panel for
resistance between (A114)J1–7 and (A114)J1–8.
Is resistance between 9,500 and 10,500
ohms?
YES
Go to step 2.
NO
Replace pilot dim/test panel
(TM 1-1520-238-23).
2. Check manual DIM control potentiometer on
pilot dim/test panel for resistance between
(A114)J1–12 and (A114)J1–8.
Does reading increase from between 0 and
500 ohms to between 9,500 and 10,500 ohms
when control knob is rotated clockwise?
YES
Go to step 3.
NO
Replace pilot dim/test panel
(TM 1-1520-238-23).
3. Check for 6.2 VDC to –6.2 VDC between:
P787–7 and ground,
P787–8 and ground.
Is voltage present?
YES
Go to step 6.
NO
Go to step 4.
4. Check for open between:
P787–12 and P400–24,
P787–7 and P400–22,
P787–8 and P400–23.
Does open exist?
YES
Repair open wire.
Go to paragraph 8–10.
NO
Go to step 5.
5. Check for short between:
P787–12 and ground,
P787–7 and ground,
P787–8 and ground.
Does short exist?
YES
Repair shorted wire.
Go to paragraph 8–10.
NO
Replace SDC
(TM 1-1520-238-23).
6. Check for open between P787–12 and P400–24.
Does open exist?
YES
Repair open wire.
Go to paragraph 8–10.
NO
Go to step 7.
7. Check for short between P787–12 and P400–24.
Does short exist?
YES
Repair shorted wire,
Go to paragraph 8–10.
NO
Replace SDC.
(TM 1-1520-238-23)
END OF TASK
