TM 55-4920-413-13&P
k. Gas Gen Speed NO 1 and NO 2.
(1) Connect frequency counter to connector NO 1 pins C
(HI) and D (LOW), using two leads and adapter.
(2) Set GAS GEN SPEED NO 1 CAL/NOR switch to
CAL and HI/LO switch to HI.
(3) Set ON-OFF-SIM ONLY switch to SIM ONLY. Fre-
quency counter will indicate between 2125 and 2145 Hz. If not,
perform Troubleshooting Table 4-14.
(4) Set GAS GEN SPEED NO 1 HI/LO switch to LO.
Frequency counter will indicate O. If not, perform
Troubleshooting Table 4-14.
(5) Set GAS GEN SPEED NO 1 CAL/NOR switch to
NOR and adjust GAS GEN SPEED NO 1 variable control
from fully CCW to fully CW. Frequency counter indication will
vary from O to 2400 Hz minimum. If not, perform Troubleshoot-
ing Table 4-14.
(6) Set ON-OFF-SIM ONLY switch to OFF.
(7) Disconnect leads from connector NO 1 pins C (HI) and
D (LOW) and connect to connector NO 2 pins C (HI) and D
(LOW).
(8) Repeat (2) through (6) above, except use GAS GEN
SPEED NO 2 controls.
Table 4-14. Troubleshooting GAS GEN SPEED NO 1 and NO 2 (AVIM).
NOTE
Before performing troubleshooting, remove Frequency Simulator A3 board and reconnect using extender board.
Trouble
Probable Cause
Remedy
HI-CAL No
NO 1– U4
First check loops 44 (-) and 17 (+)
Frequency Output or out of
U 10 Pin 7 (34,165 Hz ± 10 Hz)
for 2.130 KHz ± 10 Hz NO 1 and NO 2
tolerance
U11 pin 7 (4,271 Hz ± 1O Hz)
check, U8C in 3 (HI) U10 pin 7 (HI),
U8C pin 3 (34,165 Hz ± 10 Hz)
U11 pin 7 (HI). NO 1 check U4 pin
13 (HI). Replace defective compo-
nents, Figures 4-8, 4-9, FO-3, FO-5,
or redate A3 board.
I
HI-CAL amplitude
NO 1 – (U4B) (C32) (R57) (R56)
Replace defective components A3
affecting Frequency
NO 2 – (U4B) (C31) (R57) (R56)
board, Figures 4-8, 4-9, FO-3, FO-5,
or replace A3 board.
LO/CAL indicates Frequency
NO 1 – (S15)
Replace defective components,
greater than 0 HZ
NO 2 – (S17)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
NOR-FULLY CCW
NO 1 – (R7) (R36) (R30)
Replace defective components,
indicates Frequency greater
NO 2 (R8) (Q5) (R27)
Figures 4-8, 4-9, FO-3, FO-5, or
than 0 Hz
replace A3 board.
NOR-FULLY CW
NO 1 – (R7) (Q4) (Q9) (Q14) (U2B)
Replace defective components,
indicates NO Frequency Output
NO 2 – (R8) (Q5) (Q1O) (Q15) (U3A)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
NOR-Frequency
Trim Resistor
Replace defective components,
out of tolerance
NO 1 – (R26)
Figures 4-8, 4-9, FO-3, FO-5, or
NO 2 – (R46)
replace A3 board.
Low Amplitude affecting
NO 1 – (U2B) (C19) (R37)
Replace defective components,
Frequency
NO 2 (U3A) (C28) (R48)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
Frequency out of tolerance after
NO 1 – (R25) (C16) (Q9) (R40)
Replace defective components,
trim resistors replaced
NO 2 – (R45) (C25) (Q1O) (R51)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
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