108 Agilent 7890 Series Troubleshooting
4 GC Not Ready Symptoms
Valve Not Ready
Troubleshooting depends on the type of valve.
External valves
External valves are valves connected to the GC through the
external events or BCD connectors on the back panel
This Not Ready state means that the +24 V supply to the
pneumatics valves is actually less than +16.5 V. All valves are
disabled to prevent improper operation.
When full voltage is restored, the GC becomes ready.
This Not Ready state could indicate a hardware problem in the
external valve or in the GC analog and power board.
Gas sampling valves
The GC is normally not ready whenever the inject time or load
time has not elapsed. It becomes ready when the specified load
or inject time has passed.
Multiposition valve
A multiposition valve can cause the GC to be in a not ready
state for one of the following reasons:
• The multiposition valve is not at the setpoint position. The
GC remains not ready until the valve reaches the setpoint.
• The BCD cable is missing or not plugged into the receptacle.
If the cable is missing, the valve will never become ready.
• The BCD setpoint is incorrect for the valve BCD output
polarity. The valve will most likely shutdown with Illegal
Position or Not Switching shutdown errors.
• If the valve is plugged or the sample is viscous, the switching
time may be too short for the valve to switch. Increase the
switching time.
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