Brother Facsimile Equipment MFC7420 - Manual (Page 233)

Confidential 9-45
I-21 Horizontal lines
Possible cause Step Check Result Remedy
Paper tray
contacts 1 Are the ground contacts on
the right side of the paper
tray connecting correctly? No Clean the contacts.
Drum unit 2 Are the high-voltage power
supply and drum unit
contacted correctly? No Clean the contacts.
I-22 Light rain
Possible cause Step Check Result Remedy
Ground
contacts
Drum unit
failure 1 Is the problem solved after
replacing the drum unit? Yes Replace the drum unit.
Drum
connection
failure 2 Is the contact between the
drum unit and printer body
connected correctly? No Clean contact electrode
both on the drum unit
and in the printer body.
(7)
High-voltage
power supply
PCB failure 3 Is the problem solved after
replacing the high-voltage
power supply PCB? Yes Replace the high-
voltage power supply
PCB.