Troubleshooting - Agilent Technologies FRG-700 User Manual

Technical Information

Troubleshooting

Table 3 Troubleshooting Table
Problem
Measuring signal continually < 0.5 V
"Error low".
Measuring signal continually > 9.5 V
"Error high".
The green lamp is ON and the status
output indicates Pirani-only mode
(measuring signal continually
> 4.0 V)
Measuring signal continually
> 5 V or display
> 10-3 mbar although
vacuum pressure is OK.
Measuring signal unstable.
44 Agilent Inverted Magnetron Pirani Gauge FRG-700 and FRG-702 User Manual
Possible Causes
No supply voltage.
Pirani measurement element defective
(filament rupture).
Electronics unit not correctly mounted.
The cold cathode discharge has not
ignited.
The FRG has only been activated with
-9
p < 3×10 mbar.
Pirani measurement circuit not adjusted,
e.g. due to severe contamination.
Measurement of heavy gases.
Severe outgassing in the cold cathode
measuring chamber.
Gauge contaminated.
Remedy
Turn on the power supply.
Replace the Pirani element.
(FRG-700 page 38)
(FRG-702 page 41).
Mount the electronics unit correctly.
(FRG-700 page 38)
(FRG-702 page 42).
Wait until the gas discharge ignites
(in case of contamination with insulation
layers, the cold cathode may completely
fail to ignite).
Cleaning
(FRG-700 page 36)
(FRG-702 page 41).
Slightly increase the pressure.
Readjust the Pirani measurement circuit.
If adjustment is impossible, replace the
Pirani element.
Convert with the corresponding formula.
Clean the measuring chamber.
Clean the gauge
(FRG-700 page 36)
(FRG-702 page 41).