TM 55-4920-413-13&P
j. Engine % RPM 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 ENGINE % RPM 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 1308 and 1362 Hz. If not,
perform Troubleshooting Table 4-13.
(4) Set ENGINE % RPM NO 1 HI/LO switch to LO. Fre-
quency counter will indicate O. If not, perform Troubleshoot-
ing Table 4-13.
(5) Set ENGINE % RPM NO 1 CAL/NOR to NOR and
adjust ENGINE % RPM NO 1 variable control from fully CCW
to fully CW. Frequency counter indication will vary from O to
1830 Hz minimum. If not, perform Troubleshooting Table 4-13.
(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 Y (HI) and Z
(LOW).
(8) Repeat (2) through (6) above, except use ENGINE %
RPM NO 2 controls.
Table 4-13. Troubleshooting Engine % RPM 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 % RPM indicates no
NO 1 – U5 pin 7(61,342 Hz ± 27 Hz)
First check loops 44 (-) and (3 HI)
Frequency Output
U13 pin 7 (61,134 Hz ±27 Hz)
NO 1 for 1335 Hz ±27 Hz and check
U15 pin 7 (HI), U14 pin 7 (HI), U13
pin 7 (HI), U5 pin 7 (HI). Figures
4-9, 4-10, FO-3, FO-5, or replace A3
board.
LO-CAL
NO 1 – (S11)
Replace defective components A3
Frequency greater than 0 HZ
NO 2 – (S13)
board, Figures 4-8, 4-9, FO-3, FO-5,
or replace A3 board.
NOR-FULLY CCW
NO 1 – (R5) (R14) (R17)
Replace defective components A3
Frequency greater than 0 HZ
NO 2 (R6) (R30) (R27)
board, Figures 4-8, 4-9, FO-3, FO-5,
or replace A3 board.
NOR-FULLY CW
NO 1 – (R5) (Q2) (Q7) (Q12) (U18)
NO Frequency Output
NO 2 – (R5) (Q3) (Q8) (Q13) (U2A)
NOR-Frequency
Trim Resistor
out of tolerance
NO 1 – (R4)
NO 2 – (R23)
Replace defective components A3
board, Figures 4-8, 4-9, FO-3, FO-5
or replace A3 board.
Replace defective components,
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
Frequency out of tolerance after
NO 1 – (R3(C4) (Q7) (R18)
Replace defective components,
trim resistors checked or replaced
NO 2 – (R24) (C13) (Q8) (R31)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
Low Amplitude effecting
NO 1 – (U18) (C7) (R15)
Replace defective components,
Frequency
NO 2 (U2A) (C18) (R28)
Figures 4-8, 4-9, FO-3, FO-5, or
replace A3 board.
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