Testing Basic Functions Of The Va-10X; Open Circuit Test; Dc Accuracy - NPI VA-10X Operating Instructions Manual

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6.2.

Testing Basic Functions of the VA-10X

All tests should be made in a noise free environment (e.g. Faraday cage or metal box
connected to GROUND). Please be careful, the headstage is sensitive to electrostatic
discharges (see also chapter 1). Please note that the headstage enclosure is NOT connected to
GROUND, it is connected to the COMMAND signal applied to the microelectrode.
Special notice for 3-electrode headstage: The 3-electrode headstage differs from the standard
headstage in having an additional 1 mm electrode connector (REFERENCE) between the
GROUND and COMMAND connectors for measuring the bath potential. This signal is
processed electronically, so that the command potential is floating with respect to the bath
potential. The REFERENCE input must not be open. It has to be connected to GND for these
tests.
Before starting the tests, check that if everything is set to zero that there is no offset at the
output BNC connectors or digital meter. Also please check that the headstage enclosure
(driven shield) is also at zero, e.g. with a digital meter. Then do the following tests:

Open Circuit Test

 Do not connect anything to the electrode BNC. With no command signals, the current
should be zero.
 Connect a pulse to the command input BNC connector. You should observe only
capacitive transients and NO current during the pulse.

DC Accuracy

 Connect a 100 M or another high value resistor from the electrode BNC to ground.
Caution: Do not use the BNC shield or the headstage enclosure for grounding since they are
connected to COMMAND!
 Apply a command signal of 100 mV DC to the headstage from the COMMAND setting of
the voltammeter. Alternatively, connect a DC signal of 1 V to the INPUT ÷10 mV BNC
connector (#10, Figure 1).
Important: If an external voltage source is used, the 3-position toggle switch controlling the
internal voltage source (#6) should be set to "0". If the switch is set to "-" or "+", the voltage
at the electrode is the sum of the external voltage and the internal voltage source.
 Check with a digital meter that the headstage enclosure and the shield of the headstage
BNC connector are at the COMMAND potential of 100 mV.
 The COMMAND MONITOR output BNC should provide the correct signal of 1 V.
 At the current output BNC should be a signal corresponding to Ohm´s Law and multiplied
by the selected gain factor.
 Changing the polarity or magnitude of the command signal must lead to corresponding
output signals, especially at the CURRENT OUT BNC connectors (according Ohm´s
Law).
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version 7.0
VA-10X User Manual
page 14