64 Troubleshooting and Maintenance Manual
3 CI Troubleshooting
No or low reagent gas signal
If you have just installed the CI ion source and have an air leak or large amounts
of water in the system and have run one or more autotunes, the ion source is
probably dirty now.
Fix the air leak. Clean the ion source. Then bake out for two hours before
tuning. See the Operation Manual.
The wrong reagent gas is flowing.
Turn on the correct reagent gas for your tune file.
Ion polarity is set to Negative. No reagent gas ions are formed in NCI.
Switch to Positive ionization mode.
The reagent gas flow is set too low.
Increase the reagent gas flow.
Reagent gas supply tubing is blocked, kinked, pinched, or disconnected.
Inspect and, if necessary, repair or replace the reagent gas supply tubing.
Wrong filament wires are connected to filament.
Make sure that the filament 1 wires are connected to the CI ion source
filament and that the filament 2 wires are connected to the dummy filament.
Carbon has built up on the filament or filament has sagged out of alignment.
Inspect the filament. If necessary, replace the filament.
Too much air or water in the system.
Run the methane pretune. Peaks at m/z 32 and 19 usually indicate air and
water, respectively. Bake out and purge the instrument until there is no visible
peak at m/z 32 and the peak at m/z 19 is reduced to a very low level. If the
peak at m/z 32 does not decrease, an air leak is likely. See “Air Leaks” on
page 54 for more information.
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