Table 4-9. Troubleshooting Turbine Gas Temp NO 1 or No 2 (AVIM)

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