Maintenance
22
GA09313_0202 – (2008-02) –
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Oerlikon Leybold Vacuum
6.3 Troubleshooting
Problem
Possible
cause
Remedy
Measuring signal
continually <0.5 V
"Error low".
No supply voltage.
Turn on the power supply.
Measuring signal
continually >9.5 V
"Error high".
Pirani measurement
element defective
(filament rupture).
Replace the Pirani element
(
→
20).
Electronics unit not cor-
rectly mounted.
Mount the electronics unit
correctly (
→
20).
The green lamp is ON and
the status indicates Pirani-
only mode (measuring
signal continually >4.0 V)
"Pirani underrange".
The cold cathode dis-
charge has not ignited.
Wait until the gas dis-
charge ignites (in case of
contamination with insu-
lation layers, the cold
cathode may completely
fail to ignite).
(Cleaning
→
18).
The transmitter has only
been activated at
p <3×10
-9
mbar
Slightly increase the
pressure.
Measuring signal continu-
ally >5 V or display >10
-3
mbar although vacuum
pressure is OK.
Pirani measuring circuit
not adjusted, e.g. due to
severe contamination.
Readjust the Pirani mea-
suring circuit (
→
16). If
adjustment is impossible,
replace the Pirani element.
Measurement of heavy
gases.
Convert with the corre-
sponding formula
(
→
28).
Severe outgassing in the
measuring chamber.
Clean the measuring
chamber.
Measuring signal unstable. Transmitter conta-
minated.
Clean the transmitter
(
→
26).
