Brother MFC-9420CN Service Manual page 264

I-13 White Band
Phenomenon
White banding line appears in the horizontal direction, and consequently causes a missing image as
shown in print sample [13] of Fig.9-1.
Main Causes
(1) Deformation of the transfer roller.
(2) Contact failure of the transfer roller's bias terminal.
(3) Failure of the transfer roller clutch PU.
Fusing Unit FU
Rear cover ASSY PU
Transfer roller ASSY PU
Registration roller ASSY PU
Transfer unit PU
Paper feed roller PU
Countermeasures
(1) Replace the transfer roller ASSY PU with a new transfer roller ASSY PU.
(2) Check up the transfer roller's bias terminal.
(3) Check up the transfer roller clutch and cam structure.
Fig. 9-14
9 - 3 7
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