7 Service and Maintenance
61
Series 340 Vacuum Gauge Controller
Instruction Manual - 340005 - Rev. D
7.3.3 Ionization Gauge Filament Turn ON and Emission
7.3.4 Degas Troubleshooting
There will not be a pressure reading displayed on the front panel of the 340 Controller during a
degas function.
Table 7-4 Ion Gauge Degas Troubleshooting
Table 7-3 Filament Turn On and Emission Troubleshooting
Symptom
Possible Causes
Corrective Action
1. The ionization gauge filament does
not illuminate when the gauge switch is
toggled. The display indicates 9.9+9
and then after approximately one
second, turns OFF.
1. The gauge cable is not connected
to the gauge or to the controller.
2. An open filament in the ion gauge.
3. An open in the ion gauge cable.
1. Connect the gauge cable.
2. Replace the ion gauge or switch to
the second filament (if available).
3. Repair or replace the gauge cable.
2. The ion gauge filament does not
illuminate when the gauge switch is
toggled. The display does NOT
momentarily indicate 9.9+9.
1. Power supply voltage problem.
3. The ion gauge filament illuminates
when the filament switch is toggled ON
and then turns OFF after approximately
one second.
1. The pressure in the gauge is too
high to permit emission.
2. Normal operation. The pressure in
the gauge is greater than the
overpressure shutdown level from the
electrometer circuit.
3. Low line voltage.
4. Open in the gauge cable grid wire.
5. Grid bias supply shorted by either
the gauge or the gauge cable.
6. Degraded filament emissive
coating not providing required
emission.
1. Decrease the system pressure.
2. Decrease the system pressure or
decrease the emission by selecting a
lower emission.
3. Connect the controller to a power
line with the appropriate voltage
level.
4. Repair or replace the gauge cable.
5. Troubleshoot and repair.
6. Replace the ion gauge.
Symptom
Possible Causes
Corrective Action
The Degas switch does not turn-ON the
ion gauge and the degas indicator on
the front panel of the 340 Controller.
System pressure is too high
Turn ON the ion gauge and lower the
system pressure to less than 5 x 10
-5
Torr.
The grid in the ion gauge does not heat
up during degas, but the degas indicator
on the front panel is ON.
1. Defective ion gauge
2. The gauge cable is unplugged or
defective
1. Replace the ion gauge.
2. Check the cable connection or
replace the cable if necessary.
The ion gauge filament does not turn
ON, and no pressure reading is
displayed on the front panel of the 340
controller.
Normal operation
No corrective action required.
