Canon imageCLASS LBP6780dn Service Manual page 53

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Technology > Controller System > Low-voltage Power Supply > Safety
■ Protective function
The low-voltage power supply has a protective function against overcurrent and overvoltage
to prevent failures in the power supply circuit. If there flows an overcurrent or an overvoltage,
the system automatically cuts off the output voltage.
If the DC power is not being supplied from the low-voltage power supply, the protective
function may
be running. In such case, turn off the power switch and unplug the power cord. Do not plug in
the power cord or turn the power switch on again until the root cause is found.
In addition, two fuses in the low-voltage power supply protect against overcurrent.
If overcurrent lows into the AC line, the fuse blows and cuts off the power distribution.
■ Safety
For user and service technician's safety, the printer has a function to interrupt 24V power
supply to the fixing unit and the high-voltage power supply unit.
The door switch is turned off and 24V stops under the following condition:
• If the cartridge door is opened (SW301 is turned off)
The printer has the power switch on the DC line so the AC power flows even the power switch
is turned off. Be sure to unplug the power cord before disassembling the printer.
2 Technology > Controller System > Low-voltage Power Supply > Safety
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