barfield TT1200A User Instruction Manual page 22

8. The red clip connects to the Chromel lead and the black clip to Alumel lead.
9. Press and release the PTM pushbutton.
10. The display shows resistance in Ω with 0.01 Ω resolution.
11. If display reads "OUT OF RANGE", the resistance is greater than 199.99 Ω, or there is an
open circuit.
12. Exchange the RED and BLACK test clip connections and verify that the display repeats the
reading when the PTM pushbutton is pressed. If reading does not repeat, the engine
thermocouples may be hot. (Refer to Hot Engine Testing, Chapter 3, section 1.D.).
Note: Resistance must be within the manufacturer's specifications. If results are slightly
outside limits, repeat entire procedure to ensure test failure is not due to human error.
13. Press the PWR pushbutton to power down the Test Set.
14. Disconnect the Test Set from the aircraft wiring.
15. Return the aircraft to its original configuration.
C. Insulation Test Procedure
1. Access the aircraft system temperature indicator.
2. Disconnect one or both leads from the aircraft system indicator (refer to the engine
manufacturer's Maintenance Manual for the specific test method).
3. Connect the standard leads to the Test Set's TEST connector.
4. Press the Test Set PWR pushbutton.
5. Set the FUNCTION switch to INS MEAS.
6. Set the RANGE switch to 2 MΩ.
Note: The mV, °F and °C pushbuttons are inactive. The settings for the SYS RES,
TEMP ADJ and FINE control knobs have no effect.
7. Connect the BLACK lead clip to the aircraft ground and the RED lead clip to one or both
thermocouple system lead wires (refer to the engine manufacturers' Maintenance Manual for
the specific connections).
8. Press and release PTM pushbutton.
9. The display shows the insulation resistance in 1,000,000's of ohms (MΩ).
10. If display reads "OUT OF RANGE", the resistance is greater than 1.999 MΩ or there is an
open circuit.
Note: Resistance to ground must be no less than manufacturer's specifications.
11. Press the PWR pushbutton to power down the Test Set.
12. Disconnect the Test Set from the aircraft wiring.
13. Return the aircraft to the original configuration.
D. Indicator Test Procedure (with Specified Lead Resistance)
1. Access the aircraft system temperature indicator.
2. Disconnect the thermocouple leads from the indicator.
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