Table 1-12. Indicator and Control Functions.

TM 55-4920-401-13&P Table 1-12. Indicator and Control Functions. Indicator or Control Function . A/C IND ADJ (INCREASE) Adjusts test signal for aircraft temperature potentiometer indicator. AMB TEMP potentiometer Controls equivalent ambient temperature electrical signal for standard day correction circuit. CAL ADJ potentiometer Calibrates related indicator to internal calibration signal. DISPLAY (BRIGHT) Adjusts brightness of indicator displays. FUNCTION SELECT switch A seven-position switch that selects the circuit of the function being performed by the tester. INSULATION CHECK meter Indicates insulation resistance of engine tem- perature circuit during insulation resistance check. INSULATION CHECK switch Selects range of INSULATION CHECK meter. MASTER POWER switch Applies and removes power from tester, POWER TO TEST switch Tests all indicator displays. PROBE CONTROL potentiometer Adjusts the test temperature of the temperature probe. PROBE POWER lamp Glows while probes are heating, turns off during probe control overshoot, then blinks rapidly when test temperature is reached. RESISTANCE & A/C INDICATOR CHECK switch Places proper resistance in bridge circuit when checking resistance of engine thermocouple harness or checking aircraft indicator. RESISTANCE CHECK meter Indicates resistance error of aircraft temperature circuit. % RPM indicator Indicates N1 and N2 % rpm. RPM switch Selects N1 or N2 rpm. Calibration of % RPM indi- cator is displayed when switch is in CAL 100% RPM position. SPREAD switch With FUNCTION SELECT switch in SPREAD posi- tion, individual thermocouple signals applied to SPREAD CABLE receptacle can be read on TEMP° C indicator. In ALL position couple signals is displayed. average of all thermo- 1-42