Brother Facsimile Equipment MFC7420 - Manual (Page 231)

Confidential 9-43
I-18 Gray background
Possible cause Step Check Result Remedy
No Recommend to use the specified
types of paper. Print paper 1 Does the paper being used
meet the paper
specification (weight, etc.)
Yes Recommend to change to freshly
unpacked paper.
Toner sensor
failure
(printer side) 2 Is the error indication
displayed when the toner
cartridge and drum unit is
taken out of the machine?
(The front cover is closed.) No Toner sensor failure. Clean the
toner sensor and check the toner
sensor connection.
Toner
cartridge
failure 3 Is the problem solved after
replacing the toner
cartridge? Yes Replace the toner cartridge.
Yes Replace the drum unit. Drum unit
failure 4 Is the problem solved after
replacing the drum unit?
No Replace the high-voltage power
supply PCB.
NOTE: The following cases increase the possibility of this problem.
• Acid paper is being used.
• The drum unit is at the end of its life.
• There is dust or paper powder.