Measurement Computing Isolator488 - Manual (Page 13)

Section 2 Getting Started
2.4
As shown in the preceding diagram, the Isolator488 is shipped with a 'soft ground'
consisting of a 1 M
Ω resistor in parallel with a 0.01 µF capacitor between local
Common and Earth Ground. This configuration should be suitable for most
applications. If you wish to make any changes to this configuration, follow the
steps given below.
2.3 Modifications
The Isolator488, as shipped from the factory, is configured for the typical use
of the unit which is to isolate the instrument port from Earth ground and from
Controller common. The factory configuration should be used unless you have a
significant variation in your application beyond galvanic isolation devices on the
Instrument port. If the factory configuration is not appropriate for your
application, the following procedures may be undertaken to modify the
Isolator488. It is necessary to open the enclosure to make any of the following
changes. If yoou have any questions about a particular change, please contact the
applications department at (440) 439-4091.
1. Disconnect the power cord from the AC line and from the Isolator488.
Disconnect any IEEE cables prior to disassembly.
WARNING
Never open the Isolator488 case while it
is connected to the AC line. Internal
voltage potentials exist which could
cause personal injury or death.
2. Place the Isolator488 on a flat surface. Remove the six screws on top of the
case and remove the top cover. Located to the right of the Controller Port IEEE
488 connector are locations for C16, R4, and F2. Located to the right of the
Instrument Port IEEE 488 connector are locations for C59, R5, and F3. Refer to
the following figure: