Theory of operation
Combiner board
The Combiner board routes the 100-240 VAC input from the rear-panel line
fi
lters
to the Power Supply modules. The AC level detectors on the Combiner board
indicate if the AC level is less than about 75 V. These AC-low lines drive the
front-panel AC LEDs and the logic in the Combiner board and Main board PLD
to prevent switching if the AC inputs are low.
The Combiner takes in the 12 V from the one or two supplies, and converts
it to 5.2 V for the rest of the instrument. If there are two good supplies, the
microcontroller in the Combiner chooses the preferred one. If either supply or AC
input has an issue, the microcontroller chooses the best one.
There are two sets of 12 V storage capacitors. One set of capacitors allows time
for the system to switch supplies without any disruption of the 5.2 V output. The
second set of capacitors is used to
fl
ash the power-status LEDs for approximately
10 minutes after loss of power. During the boot up of the Combiner board
microcontroller, the Combiner functions in diode mode and uses whichever
supply has the higher voltage, or a mix of the two.
During operation, the Combiner board has a load that can be used to test the
inactive supply. This happens when a new supply is plugged in and once a day to
ensure that the backup supply can support the instrument if the primary supply
fails.
The Combiner board also drives the fans and senses if they are not spinning. The
fans are located in each Power Supply module.
ECO8000 Series Service Manual
2–9
Summary of Contents for ECO8000 Series
Page 1: ...xx ECO8000 Series Automatic Changeover Unit ZZZ Service Manual P077088000 077 0880 00...
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Page 18: ...Preface xii ECO8000 Series Service Manual...
Page 19: ...Operating basics...
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Page 26: ...Operating basics 1 6 ECO8000 Series Service Manual...
Page 27: ...Theory of operation...
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Page 38: ...Theory of operation 2 10 ECO8000 Series Service Manual...
Page 39: ...Maintenance...
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Page 66: ...Maintenance 3 26 ECO8000 Series Service Manual...
Page 67: ...Troubleshooting...
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Page 92: ...Troubleshooting 4 24 ECO8000 Series Service Manual...
Page 93: ...Replaceable Parts...
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