Figure 2-3. Thermocouple and Harness Check Setup

TM 55-4920-401-13&P . Figure 2-3. Thermocouple and Harness Check Setup. compared. Refer to figure 2-4 and proceed as follows: (1) Turn FUNCTION SELECT, STD DAY, and MASTER POWER switches to OFF position. (2) Connect BH485 instrument cable to INSTRUMENT CABLE receptacle on tester and to egt indicator check adapter. Connect BH822 egt indicator check adapter to proper terminal posts on aircraft indicator. Place RESISTANCE & A/C INDICATOR CHECK switch in proper resistance position (see indicator for circuit resistance value). NOTE If indicator is left in instrument p a n e l , o n e a i r c r a f t l e a d m u s t be disconnected If indicator is removed f r o m i n s t r u m e n t p a n e l , a m o re accurate check will be accomplished if indicator is kept in normal operating position. (3) Turn FUNCTION SELECT switch to A/C IND CHECK position, TEMPERATURE switch to OPERATE position, and MASTER POWER switch to ON position. (4) Observe reading on tester TEMP indicator a n d a d j u s t A / C I N D A D J c o n t r o l t o t e st temperature reading (usually 600 °C). (5) The difference in the indication of the tester TEMP indicator and the aircraft indicator is the error of the aircraft indicator and should not exceed allowable technical manual tolerance. (6) If aircraft indicator exceeds technical manual tolerance, repair or replace indicator. (7) If indicator is within tolerance, proceed to check resistance in paragraph d. (8) Turn FUNCTION SELECT and MASTER POWER switches to OFF position before removing cables from tester and aircraft indicator. c . N u l l - B a l a n c e T e m p e r a t u r e I n d i c a t or Check. Connect the tester to the indicator at the engine disconnect or at the indicator using the appropriate adapter as shown in figure 2-5 and proceed as follows: (1) Turn FUNCTION SELECT switch to A/C I N D C H K p o s i t i o n, R E S I S T A N C E & A / C INDICATOR CHECK switch to NULL BAL position, TEMPERATURE switch to OPERATE 2-5