Granville-Phillips Series 330, Instruction Manual, Page: 72 / 76

8 Service and Maintenance
72
Series 330 Vacuum Gauge Controller
Instruction Manual - 330004 - Rev. 02
NOTE: If measured voltages do not agree with these readings, it will be
necessary to correct this problem before proceeding further. In most cases,
correcting the power supply problem will correct the original problem as well.
8.3.3 Ionization Gauge Filament Turn ON and Emission Problems
Table 8-2 Power Supply Test Point Voltages
Test Point Voltage (VDC)
+5 +4.75 to +5.25
20 +18 to +23
+12 +11.4 to +12.6
-12 -11.4 to -12.6
+180 +170 to +190
+220 +190 to +250
Table 8-3 Filament Turn On and Emission Problem Troubleshooting
Problem Possible Cause 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. Open filament in the ion gauge.
3. 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. 1. Refer to Section 8.3.2.
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.