9
5.
Troubleshooting
5.1.
Troubleshooting
Bad electrical wiring
is a major cause of this unit malfunctions. If this unit behaves in a manner
you find unusual, first check the wiring between this unit and the SH2. Refer to the SH2 instruction
manual as well.
●
The POWER/ERROR LED is off even though power is being supplied
Cause
Action
Miswired or broken cable
Repair the wiring and check continuity with a tester.
The power supply voltage to the SH2 is not within
the specified range
Check the power supply voltage with a tester.
This unit or the SH2 is malfunctioning
Requires inspection and repairs at ULVAC.
●
The POWER/ERROR LED is flashing or the SH2 keeps outputting the error signal
Cause
Action
Filament break or short circuit
Measure filament continuity and isolation between
each pin and the case.
⇒
Replace the gauge head when there is a problem.
The gauge head is not attached
Attach the gauge head.
This unit or the SH2 is malfunctioning
Requires inspection and repairs at ULVAC.
●
No scale-over even in atmospheric pressure
Cause
Action
The measured gas is not nitrogen
This is normal. Measurements are dependent on the
type of gas.
The measured gas is nitrogen but it contains a lot of
moisture or oils
This is normal. Measurements are dependent on the
type of gas.
An environment with a large quantity of fouling
Assume internal gauge head contamination.
⇒
Replace the gauge head
●
Pressure does not reach 0.4 Pa or lower even when pumping to vacuum
Cause
Action
The actual pressure is not 0.4 Pa or lower
Check the pressure with an ionization vacuum
gauge.
Room temperature, gas temperature is different
when measuring
This is normal. Measurements are temperature
dependent.
This unit or the SH2 is malfunctioning
Requires inspection and repairs at ULVAC.
●
The pressure reading does not show a steady value.
Cause
Action
The pressure is actually fluctuating
This is normal.
This unit is affected by pump vibrations and
fluctuating
Suppress vibrations as much as possible.
Measurements are affected by the principle of the
Pirani vacuum gauge.
Attached to a location with a gas flow
Attach this unit to a location with no gas flow.
Measurements are affected by the principle of the
Pirani vacuum gauge.
The environmental temperature is fluctuating
Wait for the environmental temperature to stabilize.
Measurements are affected by the principle of the
Pirani vacuum gauge.
High temperature and low temperature gases are
flowing in
Implement corrective action such as attaching the
gauge head to a location unaffected by gas
temperature.
Measurements are affected by the principle of the
Pirani vacuum gauge.
Dirty gauge head interior
Replace the gauge head
