Agilent Technologies 6890 Series Service Manual page 563

850 Faults
Fault 221—Thermal shutdown (status message)
Fault 221—Thermal shutdown (status message)
This fault has no popup display message, only a status message.
This fault causes the GC to shut down entirely. A thermal fault is detected if
the oven or another heated zone is not within its allowable temperature range
(lower than minimum temperature or greater than maximum temperature by
25° C). Several things could cause this error:
• A problem with the electrical supply to the instrument
• A malfunction of the zone control electronics
• A shorted temperature sensor
• A shorted heater
No power will reach the oven and other heated zones. The 6890 GC will be
not ready.
Any of the following components can experience a thermal shutdown: the
oven, the inlets, the detectors, and the aux zones. In addition, problems with
electronics on the main PC board can cause a thermal shutdown.
If you see any thermal shutdown message, first turn the GC off and on.
If the error was caused by a power supply problem, the error will
disappear and the instrument will become ready. If the error reappears,
the main board, or one or more of the heater/sensor assemblies, must be
replaced.
Fault 222—Oven thermal shutdown
Status message: Oven temp too hot
The oven temperature reading indicates the oven is above its maximum
allowable temperature by at least 25° C. This indicates a defective oven heater
drive or a defective oven sensor.
No power will reach the oven and other heated zones. The 6890 GC will be
not ready.
To determine if the oven sensor is broken, its resistance must be tested.
The resistance will be 100 ohms if the sensor is working correctly; a much
larger value indicates a faulty sensor.
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Error Codes and Internal Diagnostics
Agilent 6890 Gas Chromatograph Service Manual
Jun 2001