Omega 25, 27, 26, 24 manual Service Information, Calibration Procedures, Ambient Conditions

SERVICE INFORMATION

WARNING

All service information is intended for qualified electronic mainte- nance personnel only.

1. CALIBRATION PROCEDURES

This is a two-part procedure. Products with thermocouple functions only, fol- low the Thermocouple Calibration procedure below. Products with resistance functions (RTD, thermistor, ohms) follow first the Thermocouple Calibration procedure, then the Resistance Calibration procedure.

A.THERMOCOUPLE CALIBRATION Test Equipment Required:

1.Thermocouple simulator (OMEGA CL521, or equivalent) calibrated to ITS-90.

2.Microvolt DMM (OMEGA OM7551, or equivalent)

3.Calibration cables, per Figures 11, 12, 13.

NOTE: The copper constantan cables used in Figures 12 and 13 need to be calibrated. Voltage errors in these cables should be com- pensated at the simulator.

4. Calibration cover (OMEGA 820-307-4).

Ambient Conditions:

Units should be calibrated at an ambient temperature of 23°C ±1°C, with rel- ative humidity less than 80%.

Preparation for Calibration:

11. Remove battery from unit under test (U.U.T.). Refer to Battery Installation/Replacement section in the manual.

12. Remove bottom-cover from U.U.T. Refer to Disassembly Instructions.

13. Remove calibration-jumpers J1 and J2 from printed-circuit board.

NOTE: Removal of J1, J2 causes partial loss of previously stored calibration data. Do not remove these jumpers unless recalibra- tion is intended.

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