Overcurrent/overvoltage protection
The low-voltage power supply (LVPS) has a protective circuit against overcurrent and overvoltage to
prevent failures in the power supply circuit. The low-voltage power supply automatically stops supplying
the dc voltage whenever excessive current flows or voltage abnormally increases.
If the dc voltage is not being supplied from the LVPS, the protective function might be running. In this
case, turn off the power switch and unplug the power cable. Do not turn the power switch on until the
root cause is found.
For safety, the product interrupts the power supply of +24R and +5R. The interlock switch is turned off
and +24R and +5R are stopped whenever the front or right door is opened.
Interrupting +24R stops power supply to:
●
High-voltage power supplies
◦
Image (developing) high-voltage power supply (HVPS)
◦
First-transfer high-voltage power supply
◦
Second-transfer high-voltage power supply
●
Motors
◦
Intermediate transfer belt (ITB) motor M1
◦
Drum motor M2
◦
Developing motor M3
◦
Fuser motor M4
◦
Duplex reverse and duplex feed motors
Interrupting +5R stops power supply to:
●
Laser scanner assembly
WARNING! The product power switch only interrupts dc voltage from the LVPS. The ac voltage is
present in the product when the power cord is plugged into a power receptacle and the power switch
is in the off position. You must unplug the product power cord before servicing the product.
WARNING! If you believe the overcurrent or overvoltage protection circuits have been activated, do
not connect the product power cord or turn on the product power until the cause of the failure is found
and corrected.
In addition, fuses in the LVPS protect against overcurrent. If overcurrent flows into the ac line, the fuses
melt and cut off the power distribution.
20 Chapter 1 Theory of operation ENWW
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