General Care, Troubleshooting and Service
6-25
In this dialog, press the
Zero the Electrometers
button to start the zeroing.
Or:
From the Front Panel of the instrument select
Menu|User Settings|Zero
Electrometers
.
Preferably, this should be done with a filter on the inlet. However, during the
zero measurement, the positive charger is turned off and the negative
charger is turned on at full power which generally serves the same function
if it is inconvenient to attach a filter inline.
Normally, the zero function should remove the baseline noise that has
accumulated over time.
Note:
The following section is for advanced troubleshooting and should be
used only by experienced users or with the help of a TSI
representative.
Especially after cleaning, it is important to zero the electrometers. It is also
important to make sure that the electrometers are stable. You can check
that the electrometer zero readings are stable after two repeated zero
measurements. This is possible from the Instrument Status dialog in the
software, shown above (Figure 6-25).
1. Press the
Electrometer Offsets and RMS
button. A window displays
the offsets and RMS values for each of the 22 electrometer channels
(Figure 6-26). To copy the values in this table to a clipboard, use
Copy
Table
in the right-click popup menu for this table.
2. In general, these values should be below 1000. However, it is also
important that the values are stable. When a zero is taken, the offset is
completely compensated for. Frequently zeroing of the electrometers
helps to reduce the effects of offset drift. If a channel's offset isn't
changing over time, the frequency of zeroing can be reduced.
3. Close the window and repeat the zero procedure.
4. Press the
Electrometer Offsets and RMS
button again.
5. Compare the offset values from this reading to the last values from the
previous zero. They should be similar. If they are not, allow the
instrument to warm up for another 30 minutes and perform another
zero. Repeat this until the readings are stable. If the reading does not
become stable after repeated zero procedures, the column may need to
be cleaned again.
