Ametek CEM/Humox, User Manual

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7-6 | Thermox CEM/Humox Analyzer
Thermocouple Replacement
The tip of the thermocouple is positioned in the furnace so that it is near,
but not touching the cell housing or the furnace heater coil.
To replace the thermocouple, do the following (see Figure 7-2):
1. Remove the sensor cover to expose sensor components.
2. Disconnect thermocouple wires from terminals C and D on the sensor board.
3. Remove the screw from the thermocouple mounting tab (save the screw for
installing the new thermocouple).
4. Pull the thermocouple straight up and remove it from the furnace.
5 Insert the new thermocouple into the slot in the top of the furnace. It should
go in freely; if necessary, wiggle a little to position without forcing it in. The
thermocouple should be near, but not touching the cell housing or furnace heater
coil.
6. Put the screw back in to the thermocouple mounting clamp; this secures the
thermocouple to the furnace
7. Attach the thermocouple wires to terminals C and D on the sensor board, ob-
serving polarity (yellow wire to terminal C; red wire to terminal D).
8. Using an ohm meter, check for short circuits of the heater coil to the metal
thermocouple sheath. To do this, you will need to disconnect the furnace wires
from sensor board terminals R and S. Check that neither furnace lead is short
circuited to the metal furnace cover. The resistance should be infinite. If you
measure a short circuit, loosen the screw that secures the thermocouple and
relocate slightly until resistance is infinite.
Before performing a primary calibration, first apply power to the sensor
and allow it to heat up and stabilize (approximately one hour).
9. Perform a primary calibration. (See “Primary Calibration” in the Setup Key
section for help.)
NOTE
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NOTE
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