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3-11

Confidential

Harness colors may be changed for any reason.

2 Process Drive Unit, Front Cover Sensor, Main Drive Unit

Develop Release Drive Unit, Develop Release Sensor PCB ASSY,

Toner/New Sensor PCB ASSY

Main PCB

Hook

Cable

rack

Front

CN31

CN16

CN19

CN12

CN18

Wireless LAN

cable rack

Main drive unit

PF cable rack

Process

drive unit

Main motor

Process motor

Registration

T1 solenoid

harness (BK)

Front cover sensor

Front cover

flat cable

Hook

CN45

CN30

solenoid

Main

harness ASSY

Develop

clutch harness

(BK)

Hook

ASSY

flat cable

harness (BK)

LT-drawer

sensor harness

(RD, WH)

Hook

CN21

CN10

Develop release

Toner/new sensor

Develop release drive unit

Develop release clutch harness (BL)

CN2

Main PCB ASSY

Wireless

Toner/new sensor harness ASSY

(BL, WH, RD)

Develop release

sensor harness ASSY

(BL, WH, RD)

Hook

Paper eject ASSY

Hook

sensor PCB ASSY

PCB ASSY

LAN

cable rack

Main frame L ASSY

Default Chapter4
- Table of Contents4
Safety Information13
Chapter 1 Supplemental Specifications21
- General21
- Network Connectivity23
- Service Information24
- Supplies25
- Paper27
  - Media Specifications for ADF27
- Telephone27
- FAX (Only for the Models with FAX Function)28
- Copy29
- Scanner30
Chapter 2 Error Indication and Troubleshooting31
Introduction31
- Precautions31
- Checks before Commencing Troubleshooting33
Overview35
- Cross-Section Drawing35
  - Printer Part35
  - Scanning Part36
- Paper Feeding37
  - Printer Part37
  - Scanning Part38
- Operation of each Part39
- Block Diagram41
- Main Components42
Error Indications43
- Error Codes43
- Error Message54
- Communications Error Code65
Troubleshooting69
- Error Cause and Remedy69
- Troubleshooting for Paper Feeding Problems117
- Troubleshooting for Image Defects126
  - Image Defect Examples126
  - Troubleshooting Image Defect127
- Troubleshooting for Software Problems144
  - Unable to Receive Data144
- Troubleshooting for Network Problems145
  - Cannot Make a Print through Network Connection145
- Troubleshooting for Control Panel Problems146
- Troubleshooting for Toner Cartridge and Drum Unit Problems149
- Troubleshooting for Fuser Unit Problems151
  - Fuser Unit Failure151
- Troubleshooting for Laser Unit Problems151
  - Laser Unit Failure151
- Troubleshooting for PCB Problems152
- Document Feeding Problems153
- Scanning Image Defect Troubleshooting157
  - Image Defect Examples157
  - Troubleshooting Image Defect157
- Troubleshooting of FAX Functions161
- Troubleshooting for Other Problems163
Chapter 3 Disassembly and Assembly165
Safety Precautions165
Packing166
Screw Catalogue167
Screw Torque List168
Lubrication171
Overview of Gears173
Harness Routing174
Disassembly Flow190
Disassembly Procedure192
- Lift Gear 46/Gear Z19M10193
- Back Cover/Back Cover Stopper Arm L/Back Cover Stopper Arm R194
- Fuser Cover ASSY197
- Cleaner Pinch Roller S ASSY199
- Fuser Unit201
- Cord Hook204
- Side Cover L205
- Side Cover R209
- Duplex Tray213
- MP Cover ASSY/MP Paper Guide ASSY214
- MP Link L/MP Link R217
- Front Cover218
- Front Cover Release Button/Front Cover Release Button Spring220
- Support Flap222
- Pull Arm L/Pull Arm R (A4 Model Only)223
- Back Cover Upper (Legal Model Only)224
- ADF Unit/Hinge ASSY L/Hinge R/Hinge R Support225
- ADF Document Output Support Flap237
- ADF Document Support237
- ADF Cover ASSY238
- Gear Cover239
- Separation Roller241
- ADF Separation Pad Holder (A4 Model Only)243
- ADF Separation Pad/Separation Support Film (Legal Model Only)245
- ADF Separation Spring Holder (Legal Model Only)248
- CIS Spacer250
- Second Side CIS Flat Cable/Second Side CIS Unit252
- ADF Cover/Document Detection Sensor PCB ASSY/ First Side Document Scanning Position Sensor PCB ASSY/ Second Side Document Scanning Position Sensor PCB ASSY (Duplex Scanning Model Only)259
- Document Feed Roller ASSY 2264
- Eject Film266
- ADF Motor268
- Document Cover ASSY271
- Control Panel Assy/Document Scanner Unit272
- Panel PCB Unit274
- Lcd277
- Touch Panel ASSY278
- NFC PCB ASSY (Model with NFC Only)/Panel Cover ASSY279
- First Side CIS Unit/First Side CIS Flat Cable280
- Joint Film (A4 Model Only)285
- Joint Film2 (Single-Side Scanning Model Only)286
- Joint Cover Top287
- Modem PCB Assy/Modem Flat Cable292
  - Back Cover Upper (A4 Model Only)297
  - Wireless LAN PCB300
  - Main PCB ASSY301
  - Laser Unit Flat Cable/Laser Unit303
  - Front Cover Sensor307
  - Process Drive Unit/Fuser Drive Gear Z25308
  - Main Drive Unit314
  - Develop Release Drive Unit315
  - Develop Release Sensor PCB ASSY316
  - Toner/New Sensor PCB ASSY317
  - Fuser Fan318
  - Paper Eject ASSY319
  - Toner Filter ASSY320
  - Paper Eject Origin Sensor322
  - Back Cover Sensor ASSY323
  - Eject Sensor PCB ASSY324
  - Registration Mark Sensor Unit325
  - Power Fan326
  - Low-Voltage Power Supply PCB Unit327
  - MP Paper Empty Actuator a ASSY/MP Paper Empty Actuator B330
  - MP Paper Empty/Registration Front Sensor PCB ASSY336
  - Paper Feed Unit/Joint Pin338
  - Registration Front/Rear Sensor PCB ASSY342
  - T1 Paper Feed Sensor PCB ASSY343
  - High-Voltage Power Supply PCB ASSY346
  - Air Duct Film349
  - Blower350
Disassembly Procedure (Lt-320Cl/Lt-325Cl)351
- T2 Paper Tray Unit351
- T2 Cover Rear352
- T2 Cover Left353
- T2 Cover Right354
- T2 Relay PCB ASSY355
- T2 Paper Feed Frame Unit/T2 Edge Actuator356
Chapter 4 Adjustments and Updating of Settings370
If You Replace the Main Pcb Assy370
- Installing the Firmware (Sub Firmware, Panel Firmware, Main Firmware, and High-Voltage Firmware)371
  - Checking Firmware Version371
  - Installing the Firmware371
- Initializing the EEPROM of the Main PCB ASSY (Function Code 01)373
- Setting the Serial Number (Function Code 80)374
- Restore Machine Information (Function Code 41)374
- Setting by Country (Function Code 74)374
- Motor Reset (Function Code 57)374
- Continuous Adjustments of Density and Registration Sensor (Function Code 73)375
- Acquisition of White Level Data (Function Code 55)375
- Adjustment of Touch Panel (Function Code 61)375
- Restoration of States at Factory Shipment375
If You Replace the Registration Mark Sensor Unit376
- Continuous Adjustments of Density and Registration Sensor (Function Code 73)376
If You Replace the Low-Voltage Power Supply Pcb Unit377
- Reset of Irregular Power Supply Detection Counter of Low-Voltage Power Supply PCB (Reset Counters for Parts (Function Code 88))377
If You Replace the Process Drive Unit378
- Motor Reset (Function Code 57)378
If You Replace the High-Voltage Power Supply Pcb Assy379
- Installing the Firmware379
  - Checking Firmware Version379
- Continuous Adjustments of Density and Registration Sensor379
If You Replace the Lcd Panel Assy or Panel Control Pcb Assy380
- Installing the Firmware380
  - Checking Firmware Version380
- Adjustment of Touch Panel (Function Code 61)380
- Operational Check of LCD (Function Code 12)380
If You Replace the Laser Unit381
- Continuous Adjustments of Density and Registration Sensor (Function Code 73)381
- Counter Reset of Laser Unit (Reset Counters for Parts (Function Code 88))381
If You Replace the First Side Cis Unit, Document Scanner Unit382
- Scanning and Printing Check382
If You Replace the Adf Unit, Second Side Cis Unit383
- Acquisition of White Level Data (Function Code 55) (Duplex Scanning Model Only)383
If You Replace the Fuser Unit/Pf Kit 1, 2, and Mp384
- Counter Reset of Fuser Unit or PF Kit 1, 2, and MP (Reset Counters for Parts (Function Code 88))384
Chapter 5 Service Functions385
Maintenance Mode385
- How to Enter the Maintenance Mode385
  - How to Enter the Maintenance Mode Exclusive to Service Personnel385
  - How to Enter the End User-Accessible Maintenance Mode386
- List of Maintenance-Mode Functions387
- Detailed Description of Maintenance-Mode Functions389

Brand	Brother
Model	DCP-L8400DN
Category	All in One Printer
Language	English

Brother DCP-L8400DN Service Manual

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