Figure 4-6,4-7
TM 55-4920-413-13&P
f. Turbine Gas Temp NO 1 and NO 2.
(1) Connect digital voltmeter to connector NO 1 pins L
(HI) and M (LOW), using two leads.
(2) Set TURBINE GAS TEMP NO 1 CAL/NOR switch
to CAL and HI/LO switch to HI.
(3) Set ON-OFF-SIM ONLY switch to SIM ONLY. Dig-
ital voltmeter will indicate between 33.65 and 33.95 mvdc. If
not, perform Troubleshooting Table 4-9.
(4) Set TURBINE GAS TEMP NO 1 HI/LO switch to
LO. Digital voltmeter will indicate between –0.5 and +0.5
mvdc. If not, perform Troubleshooting Table 4-9.
(5) Set TURBINE GAS TEMP NO 1 CAL/NOR switch
to NOR and adjust variable control fully CCW. Digital volt-
meter will indicate between -0.5 and +0.5 mvdc. If not, per-
form Troubleshooting Table 4-9.
(6) Adjust variable control fully CW. Digital voltmeter
will indicate 41.3 mvdc minimum. If not, perform Troubleshoot-
ing Table 4-9.
(7) Set ON-OFF-SIM ONLY switch to OFF.
(8) Disconnect leads from connector NO 1 pins L (HI) and
M (LOW) and connect to connector NO 2 pins L (HI) and M
(LOW).
(9) Repeat (2) through (7) above, except use TURBINE
GAS TEMP NO 2 controls.
Table 4-9. Troubleshooting Turbine Gas Temp NO 1 or No 2 (AVIM)
NOTE
Before performing troubleshooting, remove DC simulator A4 board and reconnect using extender board
No HI-CAL VOLTAGE
HI-CAL VOLTAGE
Indication out of tolerance
HI-CAL VOLTAGE
Indication out of tolerance after
trim resistors checked or replaced
(R13) or (R20)
LO-CAL VOLTAGE
Indication out of tolerance
Indication out of tolerance
In NOR-FULLY CCW
In NOR-FULLY
CW
Probable Cause
NO 1 – (CR2), T3, (U2)
NO 2 – (CR3), T3, (U3) associated
resistors and capacitors
NO 1 – TGT-U1
NO 2 – TGT-U2
NO 1 – (R13)
NO 2 – (R20)
NO 1 – (R54) or (R1O) (Ul)
NO 2 – (R53) (R17) or (U3)
NO 1 – (S30)
NO 2 – (S32)
NO 1 – (R20)
NO 2 – (R21)
NO 1 (R14) (R20)
NO 2 (R14) (R21)
Remedy
First check loops 56 (+) and 58 (-)
NO 1 for input 15 vac ±.5 vac and
loops 27 (+) and 30 (–) NO 2 for
15 vac ±.5 vac. Check T3 if no volt-
age. Replace defective components,
Figure 4-6, 4-7, FO-2, FO-5, or
replace A4 board.
Use decade resistor box, and check
or replace malfunctioning compo-
nents, Figures 4-6,4-7, FO-2, FO-5
or replace A4 board.
If trim resistors do not bring read-
ing in tolerance replace malfunction-
Replace malfunctioning components,
Figures 4-6, 4-7, FO-2, FO-5, or
redate A4 board.
Replace malfunctioning component,
Figures 4-6, 4-7, FO-2, FO-5 or
replace A4 board.
Replace malfunctioning components,
Figures 4-6, 4-7, FO-2, FO-5 or
replace A4 board.
NOTE
Voltage checks are also listed on figure 4-7.
4-14
