I-6
Black vertical streaks
Black and blurred vertical stripes
Possible cause
Step
Check
Result
Remedy
Drum unit
failure
1
Are the vertical streaks about 1 - 5
length at 94mm intervals?
Yes
Replace the drum
unit.
Soiling of the
paper feed
system
2
Is the paper tray of feed system on
the drum unit soiled with toner?
Yes
Clean the toner off.
Corona failure
3
Are the vertical block streak about
10mm width?
Has the corona wire cleaner failed
to return to its home position?
Yes
Return the wire
cleaner or its home
position.
Corona failure
4
Is the corona wire soiled?
Yes
Clean the corona
wire.
Scanner
window
5
Is the scanner window dirt?
Yes
Clean the scanner
window with a soft
dry cloth.
Scratch on the
drum
6
Remove the transfer roller.
Is the surface of the drum
scratched?
Yes
Replace the drum
unit.
Cleaning failure
7
Is the drum surface soiled in
streaks?
Yes
Replace the drum
unit.
Scratch on the
fixing unit
8
Is the drum surface still soiled in
streaks even after replacing the
drum unit?
Yes
Replace the fixing
unit.
Summary of Contents for HL-720
Page 1: ...SERVICE MANUAL MODEL HL 720 730 730Plus R LASER PRINTER ...
Page 36: ...II 19 1 3 10 Engine I O HL 720 Fig 2 21 shows the engine interface circuit Fig 2 21 ...
Page 37: ...II 20 HL 730 730Plus Fig 2 22 shows the engine interface circuit Fig 2 22 ...
Page 61: ... Fig 3 18 2 4 1 1 1 ...
Page 92: ...SERVICE MANUAL MODEL HL 760 R LASER PRINTER ...
Page 109: ...II 8 1 3 4 DRAM Two 4M bit DRAMs x 16bits are used as the RAM Fig 2 6 ...
Page 113: ...II 12 1 3 10 Engine I O Fig 2 12 shows the engine interface circuit Fig 2 12 ...
Page 114: ...II 13 1 3 11 Paper Feed Motor Drive Circuit Fig 2 13 ...
Page 133: ...Appendix 2 Main PCB Circuit Diagram 1 3 CODE UK3227000 B48K272CIR 1 3 NAME ...
Page 134: ...Appendix 3 Main PCB Circuit Diagram 2 3 CODE UK3227000 B48K272CIR 2 3 NAME ...
Page 135: ...CODE UK3227000 B48K272CIR 3 3 NAME Appendix 4 Main PCB Circuit Diagram 3 3 ...