Diagnostic Checks; Thermocouple Checks - Ametek Dycor CG1000-RTP User Manual

Diagnostic Checks


NOTE
Diagnostic checks are broken down as follows:
• Wiring checks
• Thermocouple checks
• Calibration/aspirator setup checks
• AC power checks
• Furnace checks
• Process pressure checks
• Cell checks

Thermocouple Checks

Thermocouple Checks
To check the thermocouple you will
need a digital volt meter and a Type
K test meter.
-
First display the thermocouple
millivolts on the front panel
display. The display should
measure a positive voltage.
- If the display measures a nega-
tive voltage, reverse the wires
leading to pins TC+ and TC- on
the backplane board.
- To check the continuity of the
thermocouple, measure resistance
across pins TC+ and TC- on the
backplane board. The resistance
should be less than 5 Ohms.
- If this doesn't solve the problem,
remove the thermocouple from
the analyzer and connect a Type
K test meter.
Display the thermocouple millivolts and cell millivolts during trou-
bleshooting as a troubleshooting aid. You may need this information
if you need to contact the factory for assistance. Be sure to always
include your analyzer model and serial number when calling the fac-
tory for technical support.
Exercise care when working on the sensor. Turn off power, allow the
unit to cool and wear gloves.
Open Thermocouple
Disconnect power to the control unit and the sensor. Mea-
sure across terminals "TC+" and "TC-" on the backplane
board with an Ohm meter. If an open is measured, replace the
thermocouple.
Shorted/Failed Thermocouple
Check that the thermocouple leads are not shorted to chassis
ground by using an Ohm meter to measure between termi-
nal TC+ on the backplane board and chassis ground, and
between terminal TC- on the backplane board and chassis
ground. If shorted, replace the thermocouple.
Using a thermometer, check the temperature of an environ-
ment. Place the thermocouple in this same environment and
check that the reading of the test meter measures the same
temperature as the thermometer. If the thermocouple measures
the temperature incorrectly (greater than 1% of expected tempera-
ture), replace the thermocouple
Error Messages & Troubleshooting
|
6-5