Brother MFC-9840CDW, DCP-9045CDN All one color, Dirt on the back of paper

All one color

Step	Cause	Check	Result	Remedy
1	Corona wire	Are the electrodes on the	Yes	Clean both electrodes.
	failure	drum unit of the
		appropriate color and
		machine body dirty?
2		Is the corona wire	Yes	Replace the drum unit.
		damaged?
3	Charge HVPS	Is the problem solved after	Yes	Replace the charge
	PCB failure	replacing the charge		HVPS PCB ASSY.
		HVPS PCB ASSY?
4	Main PCB failure	Is the problem solved after	Yes	Replace the main PCB
		replacing the main PCB		ASSY.
		ASSY?
5	Engine PCB	Is the problem solved after	Yes	Replace the engine PCB
	failure	replacing the engine PCB		ASSY.
		ASSY?
6	Laser unit failure	Is the problem solved after	Yes	Replace the laser unit.
		replacing the laser unit?

Dirt on the back of paper

User Check

- If there is dirt on the back of the paper in duplex printing, the back of the paper tray may be dirty. Clean the back of the paper tray.

Step	Cause	Check	Result	Remedy
1	Fuser unit dirty	Is the pressure roller	Yes	Print approximate 10
		ASSY dirty? Is any other		pages.
		area in the machine dirty?
			No	Replace the fuser unit.
2	Dirt in the paper	Is the paper tray or feed	Yes	Wipe dirt off.
	feed system	system on the drum unit
		dirty with toner?
3	Belt unit dirty	Is the problem solved by	Yes	Replace the belt unit.
		replacing the belt unit?
4	Waste toner box	Is the problem solved by	Yes	Replace the waste toner
	dirty	replacing the waste toner		box.
		box?

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