Agilent Technologies 5975T LTM GC/MSD, Troubleshooting And Maintenance Manual

Page: 60 / 270

60 Troubleshooting and Maintenance Guide
3
Chromatographic Symptoms
Foreline pressure is too low
If the pressures you observe are below 20 m Torr, check for the
following:
• Column (carrier gas) flow is too low
• Column plugged or crushed by an overtightened nut
• Empty or insufficient carrier gas supply*
• Bent or pinched carrier gas tubing*
• Foreline gauge is not working correctly
* These could create a fault condition in the GC that would prevent
the GC from operating.
Analyzer chamber pressure is too low
If the pressures you observe are below 1 × 10
-6
Torr, check for
the following:
• Column (carrier gas) flow is too low
• Column plugged or crushed by overtightened nut
• Empty or insufficient carrier gas supply*
• Bent or pinched carrier gas tubing*
* These could create a fault condition in the GC that would prevent
the GC from operating.
Gauge controller displays 9.9+9 and then goes blank
This indicates the pressure in the analyzer chamber is above 8 ×
10
-3
Torr.
• Solvent peak from an on-column injection
• MSD has not had enough time to pump down
• Excessive foreline pressure
• Vacuum gauge has failed
• Line voltage too low
• Turbo pump is not working correctly
Power indicator on the gauge controller does not light
• Unplugged gauge controller power cord
• Incorrect or inadequate line voltage (24 V supply)
• Failed gauge controller fuse