Metrohm 791 VA Detector - Manual (Page 33)

3.4 Startup
791 VA Detector
27
3.4.2 Zero balancing and equilibration phase
Before the first measurement is made the working electrode must be al-
lowed to equilibrate and the chart recorder or data recording instrument
must be zero-balanced. Proceed as follows:
1 Chart recorder settings
If a chart recorder is used to record the analog signals then
proceed as follows (the working electrode must not be con-
nected to the 791 VA Detector):
• Switch on 791 VA Detector.
• Set commutator 3 on the 791 VA Detector to "Stand-by".
• Set the required polarity (+ or –) with switch 20; use switch
21 to set the required voltage range for the analog output on
the 791 VA Detector (1 V or 10 mV).
• Set potentiometer 9 on the 791 VA Detector to 0.
• Use knob 8 on the 791 VA Detector to set the current sensitiv-
ity to 0.5 µ A.
• Switch on recorder.
• Set the voltage measuring range on the recorder to the same
setting as on the 791 VA Detector (1 V or 10 mV).
• Use potentiometer 10 on the 791 VA Detector to adjust the
zero point of the recorder.
2 Settings with a data recording program
If a PC recording and evaluation program is used for recording
the analog signals then proceed as follows (the working elec-
trode must not be connected to the 791 VA Detector):
• Switch on 791 VA Detector.
• Set commutator 3 on the 791 VA Detector to "Stand-by".
• Set the required polarity (+ or –) with switch 20; use switch
21 to set the required voltage range for the analog output on
the 791 VA Detector (1 V or 10 mV).
• Set potentiometers 9 and 10 on the 791 VA Detector to 0.
• Use knob 8 on the 791 VA Detector to set the current sensitiv-
ity to 0.5 µ A.
• Switch on the data recording program on the PC and start
recording data.
• If required, use potentiometer 10 on the 791 VA Detector to
adjust the zero point (so that the mV display on the PC shows
0).