Brother MFC-9420CN Service Manual page 265

I-14 Toner Drop
Phenomenon
Toner spot stain is caused on the print by toner dropping within the machine engine as shown in
sample [14] of Fig.9-1.
Main Causes
(1) Toner drops on the transfer belt due to the breakdown of the waste toner auger.
1) Mylar of the waste toner auger is deformed.
2) Waste toner is not properly collected by the waste toner auger.
(2) Toner adhering to the developer roller drops on the OPC belt.
Countermeasures
(1) Check up the cleaning brush and the waste toner auger PU.
1) Clean the perimeter of the transfer unit cleaner installation location.
2) Check if the seal is deformed or damaged. If any deformation or damage, replace the
transfer unit cleaner with a new transfer unit cleaner PU.
3) Check if the waste toner is stuck in the machine engine. If stuck, absorb and remove the
waste toner with the vacuum cleaner.
(2) Remove the toner cartridge PU.
1) Clean the toner cartridge PU.
2) Replace the toner cartridge PU with a new cartridge PU.
Fig. 9-15
9 - 3 8
print
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