Brother MFC-9840CDW, DCP-9045CDN 10.OTHERS PROBLEMS, The fan does not work, The machine is not turned on, or the LCD indication does not appear

10.OTHERS PROBLEMS

The machine is not turned on, or the LCD indication does not appear.

Step	Cause	Check	Result	Remedy
1	Harness	Is the harness of the LCD	No	Reconnect the LCD
	connection failure	panel PCB ASSY		panel PCB ASSY
	of LCD panel	connected correctly?		harness.
	PCB
2	LCD panel PCB	Is the problem solved	Yes	Replace the LCD panel
	failure	after replacing the LCD		PCB ASSY.
		panel PCB ASSY?
3	LCD panel failure	Is the problem solved	Yes	Replace the LCD panel
		after replacing the LCD		ASSY.
		panel ASSY?
4	Low-voltage	Is the problem solved	Yes	Replace the PS PCB
	power supply	after replacing the PS		unit.
	failure	PCB unit?
5	Main PCB	Is the problem solved	Yes	Replace the main PCB
		after replacing the main		ASSY.
		PCB ASSY?

The fan does not work.

(Verify the position of each fan referring to “1.4.22 Operational Check of Fans (Function code 78)” in Chapter 5.)

Step	Cause	Check	Result	Remedy
1	Harness	Is the harness of the	No	Reconnect the harness
	connection failure	appropriate fan connected		of the appropriate fan
	of the appropriate	correctly?		correctly.
	fan
2	Charge HVPS	Is the problem solved	Yes	Replace the charge
	PCB failure	after replacing the charge		HVPS PCB ASSY.
		HVPS PCB ASSY?		Replace the fuser unit
				fan (FU) and air intake
				fan (AIR).
3	Low-voltage	Is the problem solved	Yes	Replace the PS PCB
	power supply	after replacing the PS		unit. Replace the LVPS
	failure	PCB unit?		fan (PS).
4	Engine PCB	Is the problem solved	Yes	Replace the engine PCB
	failure	after replacing the engine		ASSY. Replace the
		PCB ASSY?		drum unit fan (OPC).
5	Main PCB	Is the problem solved	Yes	Replace the main PCB
		after replacing the main		ASSY.
		PCB ASSY?

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