Omega Engineering HH-21 - Service Information; Calibration Procedure

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SERVICE INFORMATION
WARNING
All service information is intended for qualified electronic
maintenance personnel only.
1. CALIBRATION PROCEDURE
Test Equipment Required:
1. Thermocouple calibrator (Omega CL521, or equivalent).
2. Calibration cable for each thermocouple type handled by unit under test
(U.U.T.):
Type K
Type J
Type T
Ambient Conditions:
Units should be calibrated at an ambient temperature of 23°C ±1°C, with rel-
ative humidity less than 80%. Avoid air currents and heat sources that can
disturb the thermal equilibrium of the U.U.T.
Procedure:
1. Turn OFF U.U.T.
2. Remove rear cover. Refer to Disassembly Instructions.
3. Remove shorting-plug J1 from circuit board. Refer to Mechanical Parts
Diagram for location (P/N CS-791).
4. Replace rear cover. Reinstall battery. Turn on U.U.T.
5. Connect input of U.U.T. to the thermocouple calibrator with a type K
cable. Use input T1 on Models HH-22 and HH-23.
6. Set calibrator output to 32°F, type K.
7. Wait for U.U.T. readout to stabilize, then press HOLD key once, and wait
a few seconds. U.U.T. should read 32.0°F ±0.5°F, type K.
8. Set calibrator to 2500°F, type K.
9. Wait for U.U.T. readout to stabilize, then press HOLD key once, and wait
a few seconds. U.U.T. should read 2500.0°F ±1.0°F, type K.
10. Replace type K cable with Type J.
11. Set calibrator output to 32°F, type J.