Brother HL-3450CN Series, Service Manual

Page: 323 / 365

CHAPTER 8 TROUBLESHOOTING
8-60
I-19 Mottle
Phenomenon
Variation of the scanning density is found in the image as shown in print sample (19) of Page
8-46 .
Main Causes
(1) The transfer unit is not fixed in place.
(2) Assembly of the transfer roller is inaccurate.
(3) THV output of the high-voltage power supply unit is not normal.
(4) Failure of the toner cartridge.
(5) Deformation of the print paper.
Countermeasures
(1) Confirm that the transfer unit is firmly locked in place.
(2) Confirm that the transfer roller is properly installed.
(3) Replace the high-voltage power supply unit with a new one. (See Section 4.3.3 of Chapter
7 .)
(4) Replace the toner cartridge with a new one.
(5) Replace the paper with new paper from a freshly opened ream.
I-20 Residual Image
Phenomenon
Image of the preceding page appears on every other page as shown in print sample (20) of
Page 8-46 .
Main Causes
(1) Cleaning failure due to lifting of the cleaning brush of the drum cleaner.
(2) Contact failure of the drum cleaner’s bias pole.
(3) Failure of the high-voltage power supply unit.
Countermeasures
(1) Check if the drum cleaner is properly installed or not.
(2) Replace the failed high-voltage power supply unit with a new one. (See Section 4.3.3 of
Chapter 7 .)