Performance Issues - Agilent Technologies VS Series Operation Manual

C.4 Performance Issues
High helium background - after a full calibration with the test port blanked off
Causes/Resolutions
1. Filament condition:
Switch filaments and perform a full calibration.
2. Contaminated ion source/spectrometer: Both filaments 1 and 2 produce a high helium
background:
a. Open the spectrometer and inspect the ion source for contamination (carbon
buildup) or noticeable discoloration (Figure C-1 on page C-6).
b. Clean or replace the ion source and filaments (Figure C-2 on page C-7).
3. Electrometer offset /noise drift:
a. Measure the voltage, with respect to ground, on the pre-amp board (Figure C-3 on
page C-7), J3 connector OUT pin.
b. Monitor the output voltage (low mV range).
c. Unplug the P1 (ion source bd. cable) cable and observe if the leak rate is 0.0E-11
and electrometer output voltage <= 5mV DC. If the leak rate and output voltage
remain unchanged or very unstable replace spectrometer header or entire
spectrometer.
4. Foreline pump oil contamination (enriched with helium):
Replace the TriScroll pump.
Unstable leak rate reading - (Test and Fine Test modes of operation)
Causes/Resolutions
1. Leak in system:
Perform a full calibration, blank off test port and leak check the system.
2. Filament - unstable/damaged:
Switch filaments and verify if instability has been eliminated.
3. Contaminated ion source: If both filaments 1 and 2 produce an unstable background
reading (Figure C-2 on page C-7):
a. Open the spectrometer and inspect ion source for contamination (carbon buildup)
or noticeable discoloration (Figure C-1 on page C-6 and Figure C-2 on page C-7).
b. Clean or replace ion source and filaments.
4. Electrometer - cooler failure (Figure C-2 and Figure C-3 on page C-7):
a. Verify that 5.0 VDC is present on the pins labeled H+ and H on the Pre-amp board.
VS Series Component Leak Detector
This page intentionally left blank.