Ametek Thermox 2000 ATEX Series User Manual page 152

Furnace Thermocouple Replacement
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7-6 | Thermox Series 2000 WDG-HPII / HPIIC - ATEX
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.
NOTE
To replace the thermocouple, do the following (see Figure 7-3):
Remove the sensor cover to expose sensor components.
Disconnect thermocouple wires from terminals C and D on the
sensor board.
Remove the screw from the thermocouple mounting tab (save the
screw for installing the new thermocouple).
Pull the thermocouple straight up and remove it from the furnace.
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.
Put the screw back in to the thermocouple mounting clamp. This
secures the thermocouple to the furnace
Attach the thermocouple wires to terminals C and D on the sensor
board, observing polarity (yellow wire to terminal C, red wire to
terminal D).
Disconnect the furnace wires from sensor board terminals R and S.
Using an ohm meter, check for short circuits of the heater coil to the
metal thermocouple sheath. 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 connect power to the
sensor and allow it to heat up and stabilize (approximately one
NOTE
hour).
Perform a primary calibration.