44 5977B Series MSD Troubleshooting and Maintenance Manual
2 General Troubleshooting
Poor sensitivity
• Incorrect tuning
• Tune file that does not match the type of analysis
• Repeller voltage is too low
• Incorrect temperatures (oven, GC/MSD interface, ion source, or mass filter)
• Incorrect sample concentration
• Leaking GC inlet
†
• Dirty GC inlet
• Incorrect split ratio
• Purge off time in splitless mode is too short
• Excessive pressure in the MSD
• Dirty ion source
• Air leak
• Poor filament operation
• Detector (HED electron multiplier) is not working correctly
• Incorrect mass filter polarity
† This could cause a fault condition in the GC that would prevent the GC
from operating.
Poor repeatability
• Dirty syringe needle
• Dirty GC inlet
• Leaking GC inlet
†
• Injection is too large
• Loose column connections
• Variations in pressure, column flow, and temperature
• Dirty ion source
• Loose connections in the analyzer
• Ground loops
† This could cause a fault condition in the GC that would prevent the GC
from operating.
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