Remedy Make sure the pump has a mul-drop address. Make sure that the commands are sent
using the mul‑drop protocol.
Fault The green Normal LED does not light or the pump does not rotate at full speed or the
pump fails while in operaon
Cause The inlet pressure is too high.
Remedy Decrease the pumping load or check for a gross leak in the system.
Cause The pump is too hot while in operaon.
Remedy
• Increase the cooling of the pump. Change from air-cooling to water-cooling (refer
to Table: Pump performance data on page 30 for maximum inlet pressure and
cooling requirements).
•
Increase cooling water ow or decrease the water temperature or do both.
• Check that external heat sources (such as system bakeout heaters) are not
excessive.
Cause The rotor does not rotate freely.
Remedy The pump bearings can be damaged. Contact us or the supplier.
Fault Ulmate pressure cannot be reached
Cause Pressure is limited by water vapour.
Remedy Bake the system and pump.
Cause The vacuum gauges are contaminated.
Remedy Clean or replace the vacuum gauges.
Cause Pumping speed is not sucient (because of poor conductance between the pump
and the gauge or the chamber is too large).
Remedy Increase the conductance or decrease the volume.
Cause Inlet pressure is more than 0.5 mbar (50 Pa).
Remedy If the interstage inlet pressure is too high, the inlet pressure at the turbomolecular inlet
is increased. Make sure that the interstage inlet pressure is less than 0.5 mbar (50 Pa).
Cause
The backing pressure is more than 10 mbar (1x10
3
Pa).
Remedy The backing pressure can be too high. Check for backing pipeline leaks. If the
throughput is high, a larger backing pump can be necessary.
Cause The high vacuum area of the system is contaminated.
Remedy Clean the high vacuum system.
Cause Check the system for leaks and contaminaon.
Remedy If a leak is found, repair it and clean the contaminaon.
Cause The inlet pressure is less.
Page 87
B8G000880_D - Fault nding
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