Brother DCP7010, DCP7020, DCP7025, MFC7420, MFC7820N

Confidential

CHAPTER 3

THEORY OF OPERATION

Contents

Main SERVICE MANUAL Page PREFACE HOW THIS MANUAL IS ORGANIZED Page TABLE OF CONTENTS Page Page Page Page Page SAFETY PRECAUTIONS To use the MFC safely Page CHOOSING A LOCATION Page CHAPTER 1 PARTS NAMES & FUNCTIONS 1.1 EQUIPMENT OUTLINE Front view Rear view 1.2 CONTROL PANEL Page 1-4 Confidential 1.3 COMPONENTS The equipment consists of the following major components: Page CHAPTER 2 SPECIFICATIONS 2.1 GENERAL Page Page Page Page Page 2-8 Confidential 2.2 SPECIFICATIONS LIST MFC7420/7820N (1/15) 2-9 Confidential (2/15) 2-10 Confidential (3/15) 2-11 Confidential (4/15) 2-12 Confidential (5/15) 2-13 Confidential (6/15) 2-14 Confidential (7/15) 2-15 Confidential (8/15) 2-16 Confidential DCP7010/7020/7025 (9/15) 2-17 Confidential (10/15) 2-18 Confidential (11/15) 2-19 Confidential (12/15) 2-20 Confidential (13/15) 2-21 Confidential (14/15) 2-22 Confidential (15/15) Page CHAPTER 3 THEORY OF OPERATION Confidential 3-1 3.1 OVERVIEW Control Section Confidential 3-2 3.2 MECHANICAL COMPONENTS Confidential 3-3 3.2.1 Scanner Mechanism Page Page Confidential 3-6 3.2.2 Printing Mechanism 3.2.2.1 Paper supply Page Page Page Page Page Confidential 3-12 3.2.2.6 Toner cartridge Printable pages 12,000 Page Page Confidential 3-15 3.2.2.7 Print process - Charging ---------- Developing Page Confidential 3-18 3.2.3 Sensors and Actuators Sensor name Sensor type Location Page Page Page 4.1 TRANSFERRING RECEIVED FAX DATA Page Page CHAPTER 5 DIS ASSEMBLY/REASSEMBLY AND LUBRIC ATION 5.1 DISASSEMBLY/REASSEMBLY Main frame L Taptite, bind B M4x12 2 0.78 0.1 (8 1) Main fram e R Page Confidential 5-4 Disassembly Flowchart 33 (1) Disconnect AC cord from the machine. Confidential 5-6 5.1.3 Paper Tray (1) Close the front cover and pull out the paper tray. (2) Remove the paper from the paper tray. (3) Remove the separation pad holder ASSY and the separation pad spring. Page (1) Remove the rear chute cover. (2) Remove the paper eject actuator and the eject actuator spring. Confidential 5-9 5.1.6 Side Cover L (1) Remove the two bind B M4x12 taptite screws, and then remove the side cover R. Page Page Page Confidential 5-14 Confidential 5-15 (16) Remove the separation rubber ASSY from the upper document chute. (17) Remove the separation rubber from the ADF plate spring. Confidential 5-16 (20) Release the hook on the ADF unit and remove the ejection roller ASSY. Page Page Page Page (32) Remove the document front actuator from the lower document chute. Confidential 5-22 (41) Remove the two springs. (42) Remove the pressure roller ASSY. Page Confidential 5-25 5.1.9 Pull Arm/Pull Arm Guide/Lock Claw Pull Arm Spring (3) Remove the pull arm springs and remove the pull arms (R, L) from the pull arm guides. Confidential 5-26 5.1.10 Scanner Unit (1) Disconnect the flat cable from the main PCB. (2) Remove the scanner unit from the machine. 5.1.11 Panel Unit Confidential 5-27 Confidential 5-28 (8) Release the two hooks A to remove the backlight guide. (9) Remove the diffusion film. Confidential 5-30 5.1.12 NCU PCB (1) Disconnect the connector of the speaker from the main PCB. Confidential 5-32 (2) Release the three hooks to remove the speaker cover. (3) Release the one hook to remove the speaker hold spring. Confidential 5-33 (4) Remove the speaker ASSY. (1) Remove the bind B M4x12 taptite screw, and then remove the rear cover stopper. Page (4) Remove the battery ASSY and disconnect the connector. Confidential 5-36 (1) Release the hook of the drive release cam from the front cover ASSY. (4) Remove the paper stopper L. (5) Remove the paper stopper S from the paper stopper L. Page Confidential 5-39 Page Confidential 5-41 NOTE: Be sure not to touch the pressure roller. Confidential 5-43 (5) Remove the two PR arm ASSY and two PR bush from the pressure roller. Page Page Confidential 5-46 (10) Remove the HR gear. (11) Remove the two HR bush. Page Confidential 5-48 5.1.18 High-Volt ag e PS PCB ASSY Confidential 5-49 (1) Disconnect the thirteen connectors from the main PCB. Confidential 5-50 < MFC7820N > (1) Disconnect the thirteen connectors from the main PCB. Confidential 5-51 5.1.20 PS PCB Unit (7) Remove the LV insulation sheet. (10) Remove the two flat S M3x8, taptite screws, and then remove the inlet harness ASSY. Page Page Page Page Page Confidential 5-59 5.1.26 Regist Sensor PCB ASSY 5.1.27 Regist Rear Actuator/Regist Rear Spring (1) Remove the regist rear spring. (2) Remove the regist rear actuator. Page Confidential 5-61 5.1.29 Toner LED PCB ASSY/LED Holder (1) Remove the toner LED PCB ASSY from the main frame R. (2) Remove the LED holder from the toner LED PCB ASSY. 5.1.31 New Toner Sensor (1) Release the two hooks and remove the new toner sensor from the main frame L. Confidential 5-63 (1) Release the two hooks and remove the cover sensor from the main frame L. (1) Remove the cup B M3x6, taptite screw, and then remove the toner sensor PCB ASSY. Confidential 5-64 (3) Remove the three cup S M3x6, taptite screws, and then remove the main motor ASSY. (1) Remove the develop joint from the gear plate calking ASSY. (1) Remove the gear ASSY from the main frame L. Page (1) Remove the two bind B M4x12, taptite screws, and then remove the main frame L. (1) Remove the three bind B M4x12, taptite screws, and then remove the main frame R. Confidential 5-70 5.1.40 Harness Routing Laser unit FG harness ASSY 1 / FG harness ASSY 5 Confidential 5-71 FG harness ASSY 6 Regist sensor PCB ASSY Confidential 5-72 Fan motor 60 unit Toner LED PCB ASSY Toner sensor PCB ASSY P/R solenoid ASSY / F/R solenoid ASSY Confidential 5-74 9 10 Confidential 5-75 11 ADF unit 12 NCU PCB NCU FG harness 15 5.2 LUBRICATION Page CHAPTER 6 ADJUSTMENTS AND UPDATING OF SETTINGS, REQUIRED AFTER PARTS REPLACEMENT CONTENTS 6.1 IF YOU REPLACE THE MAIN PCB Page Page Page Page CHAPTER 8 MAINTENANCE MODE CONTENTS 8.1 ENTRY INTO THE MAINTENANCE MODE 8.2 LIST OF MAINTENANCE-MODE FUNCTIONS 8.3 USER-ACCESS TO THE MAINTENANCE MODE Page 8.4 DETAILED DESCRIPTION OF MAINTENANCE-MODE FUNCTIONS Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page +- +-+- Page Page Page Page Page Page Page CHAPTER 9 ERROR INDICATION AND TROUBLESHOOTING 9.1 ERROR INDICATION Page Page Page Page Page Page Page Page Page Page Page Page Page 9.2 TROUBLESHOOTING Page Page Page Page Page Page Page Page Page Page Page Confidential 9-27 [ 4 ] Image defects 1-1 Light 1-2 Dark 1-3 Completely blank 1-4 All black 1-5 Dirt on the back of paper Page Page I-3 Completely blank Laser scanner unit assy Interlock lever Page I-5 Dirt on the back of paper I-6 Black and blurred vertical streaks I-7 Black and blurred horizontal stripes I-9 White vertical streaks I-11 Faulty registration Page Confidential 9-38 I-13 Image distortion Yes Replace the laser unit. Possible cause Step Check Result Remedy Laser unit installation 1 Is the laser unit secured to the frame incorrectly? (Check if there is any play.) I-15 White spots Confidential 9-40 (2) Turn the drum gear by hand while looking at the surface of the exposure drum. I-16 Black spots I-17 Black band I-18 Gray background I-19 Hollow print Page I-23 Ghost Page Page Page Page Page Page Page Page Page Page Page Page Page Page SERIAL NUMBERING SYSTEM (2) Laser unit serial label Page A2.1 INSTALLING THE UPDATE DATA TO THE MACHINE Page Page Page Page Page Page Page A2.2 SETTING ID CODES TO MACHINES Page EEPROM CUSTOMIZING CODES Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Confidential

Brother - page 44

Models: DCP7010 DCP7020 DCP7025 MFC7420 MFC7820N