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TM 55-4920-412-13&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, HI/LO switch to HI and variable control
fully CW.
(3)
Set ON-OFF-SIM ONLY switch to SIM
ONLY. Frequency counter will indicate between 2134.3
and 2136.3 Hz. If not, perform Troubleshooting Table
4-14.
(4)
Set GAS GEN SPEED NO 1 HI/LO switch
to LO. Frequency counter will indicate 0. If not, perform
Troubleshooting Table 4-14.
(5)
Set GAS GEN SPEED NO 1 CAL/NOR
switch to NOR. Frequency counter will indicate between
2,375 and 2,480 Hz.
(6)
Adjust GAS GEN SPEED NO 1 variable
control fully CCW. Frequency counter will indicate 0 Hz.
If not, perform Troubleshooting Table 4-14.
(7)
Set ON-OFF-SIM ONLY switch to OFF.
(8)
Disconnect leads from connector NO 1
pins c (HI) and d (LOW) and connect to connector NO 2
pins e (HI) and d (LOW).
(9)
Repeat (2) through (7) above, except use
GAS GEN SPEED NO 2 controls.
Table 4-14. Troubleshooting GAS GEN SPEED NO 1 or NO 2 (AVIM)
NOTE
Before performing troubleshooting, remove frequency simulator A3 board and
reconnect using extender board.
Trouble
Probable Cause
Remedy
HI-CAL No Frequency
NO 1 - U4
First check loops 44 (-) and 17 (+))
Output of out of tolerance
U10 Pin 7 (34,165 Hz ± 10 Hz)
for 2135.3 ± 1.0 Hz NO 1 and NO 2
U11 pin 7 (4,271 Hz ± 10 Hz)
check, U8C pin 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 components,
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
HI-CAL amplitude affecting
NO 1 - (U4B)(C32)(R57)(R56)
Replace defective components A3
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 than
NO 2 - (S17)
Figures 4-8, 4-9, FO-3, FO-5, or
0 Hz
replace A3 board.
NOR-FULLY CW
NO 1-(R7)(Q4)(Q9)(Q14)(U2B)
Replace defective components
greater than 0 Hz
NO 2-(R8)(Q5)(Q10)(Q15)(U3A)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
NOR-Frequency out of tolerance
Trim Resistor
Replace defective components
NO 1 - (R26)
Figures 4-8, 4-9, FO-3, FO-5, or
NO 2 - (R46)
replace A3 board.
Low Amplitude affective Frequency
NO 1-(U2B)(C19)(R37)
Replace defective components
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 resistor replaced
NO 2-(R45)(C25)(Q10)(R51)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
4-22 Change 2
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