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3-14

Confidential

Harness colors may be changed for any reason.

7 Registration Mark Sensor Unit

8 Fuser Fan, Power Fan

Front

A view

“A”

CN43

CN44

“A”

Main PCB ASSY

Hook

Hole

Main frame L ASSY

Registration mark sensor unit

Registration mark sensor L PCB harness

Registration mark sensor

R PCB harness

(RD, WH, BL)

(GY)

Front

Hook

CN5

CN4

High-voltage power supply PCB ASSY

Main frame R ASSY

Fuser fan

Power fan

Hook

Fuser fan harness

(RD, WH, BK)

Power fan harness

(RD, BK)

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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