
PlasmaQuant MS Series
Power
Supply
201
Assuming that the CPU board is working correctly (including its interface Tx section),
the next step is to check the diagnostic LEDs on both boards while the test software
and firmware are running. The following are the basic test guidelines:
If both diagnostic LEDs (D1402 on the HV PS board and LED10 on the CPU board)
are flashing in the same manner at the same time then it is unlikely that the
interface circuit of the power supply board and the interface cable are the cause of
the problem. In that case the problem may be with the Rx interface section of the
CPU board.
If under the same test conditions the LED on the power supply board flashes, but
the one on the CPU board does not, then any of the following may be the cause:
–
the CPU interface receiving section may not work,
–
cable may have some faults or not being properly connected
–
driver for the interface Dout signal on the IO HV PS does not work.
If neither LED flashes, then the following may be the cause:
–
the Rx section on the IO HV PS does not work
–
the problem may be the cable related
–
the Tx section on the CPU board does not work correctly, including the test
software and firmware
NOTE
This test does not examine the interface part used by the detector power supply.
Measurement of output voltages
The actual value seen at the HV outputs is not fed back to the firmware, so these
outputs must be measured to confirm board functionality.
Voltages of all 12 outputs can be measured by commonly available multimeters and
probes and without removing protective cover.
However, the multimeters and probes must be rated for at least 1 kV and comply
requirements for 600V/CAT IV and 1000V/CAT III. Access to the test points is via
inspection holes of the enclosure bank panel. The test points for outputs with nominal
voltages of 1 kV and greater use voltage dividers so that multimeters rated to 1 kV can
be used. All other test points are connected directly to the outputs.
For a board that is working correctly, any of the output voltages can be set to any value
within its nominal range. The quickest way to examine an output is to check it for a set
of typical values, such as: 0%, 100%, 50%, 25% and 75% of the range (in the given
order), or to change an output in steps that are easy to check, for example, a 1 kV
rated output can be examined in step changes of 200 V.
If the measured voltage is significantly different from the expected value, then one of
the following may be the cause:
the regulator is faulty, or
the DAC output is incorrect (likely if the output status fault flag is not detected), or