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TM 55-4920-412-13&P
e. Fuel Quantity NO 1 and NO 2.
(1)
Connect Digital multimeter to connector NO 1
pin G (HI) and H (LOW), using two leads.
(2)
Set FUEL QUANTITY NO 1 CAL/NOR switch to
CAL, HI/LO switch to HI and variable control full CW.
(3)
Set ON-OFF-SIM ONLY switch to SIM ONLY.
Digital multimeter will indicate between +6.120 and
+6.130 vdc. If not, perform Troubleshooting Table 4-8.
(4)
Set FUEL QUANTITY NO 1 HI/LO switch to LO.
Digital multimeter will indicate between -1.0 and +1.0
mvdc. If not, perform Troubleshooting Table 4-8.
(5)
Set FUEL QUANTITY NO 1 CAL/NOR switch to
NOR and adjust variable control fully CCW. Digital
multimeter will indicate between -10.0 and +10.0 mvdc.
If not, perform Troubleshooting Table 4-8.
(6)
Adjust variable control fully CW. Digital
multimeter will indicate between +7.630 and +8.030 vdc.
If not, perform Troubleshooting Table 4-8.
(7)
Set ON-OFF-SIM ONLY switch to OFF.
(8)
Disconnect leads from J1 connector NO 1 pins
G (HI) and H (LOW) and connect to connector NO 2 pins
G (HI) and H (LOW).
(9)
Repeat (2) through (7) above, except use FUEL
QUANTITY NO 2 controls.
Table 4-8. Troubleshooting Fuel Quantity NO 1 or NO 2 (AVIM)
NOTE
Before performing troubleshooting, remove DC simulator A4 board and reconnect
using extender board.
NOTE
Voltage checks are also listed on Figure 4-7.
Trouble
Probable Cause
Remedy
Fuel Quantity
CR,C3,U1,R8,T2,R9,C1,
Fist check loops 7(+) and 8(-) for
No HI-CAL VOLTAGE
NO 1 - (R2) or
input 15 vac t.5 vac. Check 7T2 if no
NO 2 - (R5)
voltage. Replace defective components
Figure 4-6, 4-7, FO-2, FO-5 or
replace A4 board.
HI-CAL VOLTAGE
Trim Resistors
Remedy, use decade resistor box,
Indication out of tolerance
NO 1 - (R3)
and replace malfunctioning
NO 2 - (R6)
components, Figures 4-6, 4-7, FO-2,
FO-5 or replace A4 board.
HI CAL VOLTAGE
NO 1 - (R56) or (R9)
Output of U1 should read between
Indication out of tolerance after
NO 2 - (R55)
11.9 and 12.1 vdc at TP1, Figures 4-6,
trim resistors checked or replaced
4-7, FO-2, FO-5 or replace A4 board.
(R3) or (R6)
LO-CAL VOLTAGE
NO 1 - (S26)
Replace malfunctioning components,
Indication out of tolerance
NO 2 - (S28)
A4 Board, Figures 4-6, 4-7, FO-2,
FO-5.
LO-CAL VOLTAGE
NO 1 - (R12)
Replace malfunctioning component
Indication out of tolerance in
NO 2 - (R13)
A4 Board. Figures 4-6, 4-7, FO-2,
NOR-FULLY CCW
FO-5.
IN NOR-FULLY
NO 1 (R1) (R12)
Replace malfunctioning components
CW
NO 2 (R13) (R55)
A4 Board, Figures 4-6, 4-7, FO-2,
FO-5.
Change 2 4-13
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