Chapter 5 Troubleshooting
5.5 Repla cing the Interna l Fuse f or Dega s M ode
The display will show the error message Current limit if Degas mode cannot start. If there are no abnormal thermal or
pressure conditions in the chamber, this message probably means that the internal fuse for Degas mode has blown.
To replace the internal fuse:
1. Switch off the PU IQE 12/38.
2. Remove the four screws on the emission regulation module on the rear panel. This is the module that contains
the fan.
3. Pull out the module with care and remove the top plastic sheet.
4. Locate the fuse in the module, as shown in Figure 30.
Figure 30: Location of internal fuse
5. Replace the fuse with an identical type—50 mA, slow blow.
After replacing the fuse, reassemble the PU IQE 12/38 by carrying out the above procedure in reverse order.
Before switching the unit back on, make sure that you understand the reason why the fuse blew in the first place.
Note: Make sure that you are operating the PU IQE 12/38 according to the procedures described in "Basic Oper-
If Degas mode was started with a fully gas loaded filament or bad vacuum conditions in the surrounding volume, a rapid
increase in gas pressure could occur, igniting an ionization by impact and consequently making a temporary short circuit.
If you think this is the problem, you can condition the filament. Please refer to the manual of your ion source for instruc-
tions on filament conditioning.
5.6 Service M ode
Service mode allows you to access additional parameters and to avoid function locking by errors (e.g. because of a miss-
ing filament etc.). You can switch on high voltage without connecting the PU IQE 12/38 to the ion source.
Danger—High Voltages Present!
When in service mode, high voltages can be present on unconnected cables. Only qualified personnel
should perform tests on the instrument when it is in service mode.
PU IQE 12/383.0
April 26, 2013
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