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User Manual - Rev AJ
5.4 System Interface Board
The System Interface Board is located in the top section of the MX unit. To access this
assembly, the top cover needs to be removed. The System Interface board, A6, receives the
oscillator signal from the CPU controller assembly for all phases and passes it through to all
three amplifiers whose gains are controlled by a signal from the over current circuit. The over
current circuit senses the RMS value of the current. If the load current exceeds the
programmed value, the output of this sensing circuit reduces the amplitude of the oscillator drive
signal. The output
dropping as the load increases.
The System interface also monitors a variety of status signals from the amplifiers. This inclu
PFC good, over temperature signals and DC bus regulation good signals. If any status signal
false, the system interface board will shut down the MX. At power on, all status signals have to
return good (TRUE) or the MX system power u
Finally, the System inter
between multiple MX45 chassis for multi-box configurations (MX60, MX90 and MX135). A DB-
37 to DB-37 system interface cable is used to connect two or more MX units in a multi-box
configuration. Each MX30 or MX45 provides two sets of system interface connectors on the
rear-panel. One is the master out (unit with CPU controller assembly installed), the other the
Auxiliary in. ((unit without CPU controller or with CPU controller disabled.) The CPU controller
can be disabled using the internal DIP switch located on the GPIB / RS232C / IO assembly.
(Requires removal of the top cover).
5.5 Current / Voltage Sensor Board
The current and voltage sensor board, A4, senses the output current and voltage of all three
amplifiers and feeds this information back to the system interface board. These same signals
are also used by the controller for all measurement functions. Voltage sense is accomplished
either internally or externally. For best voltage regulation at the EUT, external sense connections
should be made using the External Sense terminal block located at the top of the back-panel.
Alternatively, internal sense mode may be selected. In this case, the voltage is sensed at the
sensor board.
5.6 Low Voltage Power Supply
The Low Voltage power supply is mounted behind the system interface board in the top section
of the MX chassis. This assembly generates all required low voltage DC outputs. These
outputs from the LV Power supply provide analog and logic power to all the modules.
a) +/- 19 V to the System Interface board and power modules.
b) + 9 V to the oscillator.
c) + 24 V to all contactors and LV cooling fan.
d) Isolated + 8 V for the GPIB/RS232 board.
Two green LED's on the system interface board are lit when the ± 15 V and ± 19 V are in
regulation. If an overload condition causes the output to drop more than 10% or the output has
failed, the corresponding LED will extinguish. This feature is helpful in troubleshooting the unit.
See Service section 6.
150
of the unit then becomes a constant current output, with the output voltage
face assembly also routes the required system interface bus signals
p sequence will be halted.
California Instruments
des
is
MX Series
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