Specifications

CI Troubleshooting 3
5975 Series MSD Troubleshooting and Maintenance Manual 69
No peaks
When troubleshooting “no peaks” it is important to specify what mode of
operation is being used and what expected peaks are not being seen. Always
start with methane PCI and verify presence of reagent ions.
No reagent gas peaks in PCI
If MSD has been working well and nothing seems to have been changed
Wrong tune file loaded, or tune file corrupted
Wrong ion polarity (there are no reagent ions visible in NCI)
No reagent gas flow; look for background ions and check pressure
Wrong reagent gas selected for the tune file (looking for wrong ions)
Large air leak
Dirty ion source
Poor vacuum (pump problem). See page 64.
If MSD was recently switched from EI to CI
Interface tip seal not installed
No reagent gas flow
Analyzer not sealed (big air leak)
Wrong tune file loaded or tune file corrupted
Ion source not assembled or connected correctly
Wrong reagent gas selected for the tune file (looking for wrong ions)
No PFDTD peaks in PCI
Incorrect reagent gas. There are no PCI PFDTD peaks created with
isobutane or ammonia. Switch to methane.
Analyzer not sealed (big air leak)
No calibrant in vial
Defective calibration valve(s)
Air leak in carrier or reagent gas path