82 tinb29e1-c (2019-10) VGC083A_B.om
OVERPRESSURE The calculated pressure is greater than
maximum setting for emission current
Change to 100
µA emission current which
will operate at higher pressures
EMIS FAIL
The desired emission current (IE) could not
be established
Gauge contamination, possible coating on
filament or grid surfaces
End of filament life
Switch to 4 mA or 10 mA emission cur-
rent and attempt repeated filament starts
to clean filament
Switch to second filament, degas
Replace the Ion gauge sensor tube
LV Failure The Filament voltage could not be estab-
lished; Electronics Failure
Contact INFICON
F1 or F2 OPEN Filament 1 or 2 is open Switch to the other filament or replace the
CONNECT IG
IG not connected
Faulty cable
Internal PCB not communicating
Plug in IG
Replace cable
OVER TEMP Ion gauge cable is longer than 50 ft. Reduce cable length to less than 50 ft. or
provide airflow around the VGC083
Once the cause of the IG error has been determined and resolved, the IG error
must be cleared before the IG filament can be turned on again. To clear errors,
simply press the IG ON/OFF key.
The OLED setup screen of the VGC083 can be configured to display important, cri-
tical operating parameters of the ionization gauge. These parameters can be dis-
played in the Research display mode as described below.
In addition to the normal pressure measurement screen VGC083 provides a diag-
nostic display screen that allows you to monitor the measurements of the critical
electrical parameters used for measurement of very low pressures, i.e., high
vacuum, made by the ionization gauge.
Over time, the hot cathode (filament) of the ionization gauge may degrade. The IG
coated iridium filaments are made using yttrium oxide to lower the work function of
the heated wire material and enable substantial emission of electrons from the hot
cathode. These electrons are accelerated in an electric field toward the grid struc-
ture of the ionization gauge device. The electron emission is commonly referred to
as the 'Emission Current'. As the emission current electrons orbit within the electric
field formed by the bias voltages applied to the grid, collector and filament elec-
trodes, the molecules that the gas is comprised of will be ionized by these ener-
getic electrons.
The positive ions that are created within the grid structure are captured in another
electric potential field created by the grid structure (at +180 V (dc) with respect to
ground potential) and the collector wire (at zero volts, i.e., ground potential). In
simple terms, the ions collected by the collector electrode (a small diameter wire
within the grid electrode structure) are measured with an electrometer circuit
connected to the collector. The amount of ion current measured is directly pro-
portional to the density of the gas within the ion gauge head. This ion current is
commonly referred to as the 'Collector Current'.
10.3 Troubleshooting - IG
10.4 Clearing Error
10.5.1 Research Screen
(Diagnostic Display - IG)
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