Color LaserJet Pro M452
HP Color LaserJet Pro M452, Color LaserJet Pro M477, Color LaserJet Pro M377 Troubleshooting Manual and Repair Manual
Troubleshooting Manual
Color LaserJet Pro M452
Color LaserJet Pro MFP M477
www.hp.com/support/colorlj452
www.hp.com/support/colorlj477MFP
For printer part removal and part number
information, see the Repair Manual.
M452nw
M452dn
M452dw
M477fnw
M477fdn
M477fdw
Color LaserJet Pro MFP M377
M377dw
www.hp.com/support/colorljM377MFP
HP Color LaserJet Pro M452, HP Color
LaserJet Pro MFP M477, HP Color LaserJet
Pro MFP M377
Troubleshooting Manual
Copyright and License
Trademark Credits
© Copyright 2016 HP Development Company,
L.P.
Reproduction, adaptation, or translation
without prior written permission is prohibited,
except as allowed under the copyright laws.
The information contained herein is subject to
change without notice.
The only warranties for HP products and
services are set forth in the express warranty
statements accompanying such products and
services. Nothing herein should be construed
as constituting an additional warranty. HP shall
not be liable for technical or editorial errors or
omissions contained herein.
Edition 3, 4/2016
Microsoft®, Windows®, Windows® XP, and
Windows Vista® are U.S. registered trademarks
of Microsoft Corporation.
Conventions used in this guide
TIP: Helpful hints or shortcuts.
NOTE: Information that explains a concept or how to complete a task.
Reinstallation tip: Reinstallation helpful hints, shortcuts, or considerations.
IMPORTANT: Information that help the user to avoid potential printer error conditions.
CAUTION: Procedures that the user must follow to avoid losing data or damaging the printer.
WARNING! Procedures that the user must follow to avoid personal injury, catastrophic loss of data, or
extensive damage to the printer.
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iv Conventions used in this guide ENWW
For additional service and support information
HP service personnel, go to the Service Access Work Bench (SAW) at http://h41302.www4.hp.com/km/saw/
home.do.
Channel partners, go to HP Channel Services Network (CNS) at https://h30125.www3.hp.com/hpcsn.
At these locations, nd information on the following topics:
●
Install and congure
●
Printer specications
●
Up-to-date control panel message (CPMD) troubleshooting
●
Solutions for printer issues and emerging issues
●
Remove and replace part instructions and videos
●
Service advisories
●
Warranty and regulatory information
To access HP PartSurfer information from any mobile device, go to http://partsurfermobile.hp.com/ or scan
the Quick Response (QR) code below.
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vi For additional service and support information ENWW
Table of contents
1 Theory of operation ....................................................................................................................................... 1
For additional service and support information ................................................................................................... 2
Basic operation ...................................................................................................................................................... 3
Sequence of operation ........................................................................................................................ 4
Formatter-control system ..................................................................................................................................... 6
Sleep delay .......................................................................................................................................... 6
Auto On / Auto O mode ..................................................................................................................... 6
Printer job language (PJL) ................................................................................................................... 7
Printer management language (PML) ................................................................................................. 7
Control panel ....................................................................................................................................... 7
Walk-up USB ........................................................................................................................................ 8
Wireless ............................................................................................................................................... 8
Low end data model (LEDM) overview ................................................................................................ 8
Advanced control language (ACL) overview ........................................................................................ 8
NFC ....................................................................................................................................................... 9
CPU ....................................................................................................................................................... 9
Input/output (I/O) ................................................................................................................................ 9
USB .................................................................................................................................... 9
USB hosts .......................................................................................................................... 9
10/100/1000 networking ................................................................................................. 9
Fax ..................................................................................................................................... 9
Memory ............................................................................................................................. 9
Firmware ......................................................................................................... 9
Nonvolatile random access memory (NVRAM) .............................................. 9
Flash memory ............................................................................................... 10
Random access memory .............................................................................. 10
HP Memory Enhancement technology (MEt) ............................................... 10
Engine-control system ........................................................................................................................................ 11
Engine-control unit ........................................................................................................................... 11
DC controller ................................................................................................................... 13
High-voltage power supply ............................................................................................ 14
Motors ............................................................................................................................. 16
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Fans ................................................................................................................................. 17
Low-voltage power supply ................................................................................................................ 18
Over-current/over-voltage protection ........................................................................... 18
Fuser control ..................................................................................................................................... 20
Fuser heater protection .................................................................................................. 21
DC controller ................................................................................................. 22
Fuser heater safety circuit ............................................................................ 22
Temperature fuse ......................................................................................... 22
Fuser control functions ................................................................................................... 22
Engine laser/scanner system .............................................................................................................................. 23
Laser/scanner failure detection ........................................................................................................ 24
Image-formation system .................................................................................................................. 25
Image-formation process ............................................................................................... 28
Step 1: Primary charging .............................................................................. 29
Step 2: Laser-beam exposure ...................................................................... 31
Step 3: Development .................................................................................... 31
Step 4: Primary transfer ............................................................................... 32
Step 5: Secondary transfer ........................................................................... 32
Step 6: Separation ........................................................................................ 33
Step 7: Fusing ............................................................................................... 33
Step 8: Drum cleaning .................................................................................. 33
Toner cartridges ................................................................................................................................ 35
Design ............................................................................................................................. 35
HP Cartridges with JetIntelligence ................................................................................. 36
HP Cartridge Policy ....................................................................................... 36
Anti-theft or cartridge protection ................................................................ 36
Memory chip .................................................................................................................... 37
Toner seal ........................................................................................................................ 37
Toner cartridge life detection ......................................................................................... 37
Developing unit engagement and disengagement control ........................................... 37
Intermediate transfer belt (ITB) unit ................................................................................................. 38
Secondary transfer roller functions ............................................................................... 38
Color self calibration ....................................................................................................... 40
Engine pickup, feed, and delivery system ........................................................................................................... 41
Photo sensors and switches ............................................................................................................. 41
Motors, clutches, and solenoids ........................................................................................................ 43
Feed speed control .......................................................................................................... 44
Pickup and feed delivery features .................................................................................. 44
Tray 1 (multipurpose)/Tray 2 (base printer) ..................................................................................... 45
Duplexing unit ................................................................................................................................... 45
Duplexing reverse and duplex feed control ................................................................... 46
viii ENWW
Duplex pickup operation ................................................................................................. 46
Jam detection/prevention ................................................................................................................. 46
Input accessories ................................................................................................................................................. 48
Tray 3 ................................................................................................................................................. 48
Tray 3 paper feeder controller ........................................................................................ 48
Tray 3 motor control ....................................................................................................... 49
Tray 3 paper pickup ......................................................................................................... 49
Tray 3 pickup and feed functions ................................................................................... 50
Tray 3 jam detection .......................................................................................................................... 50
Scanning and image capture system .................................................................................................................. 52
Document feeder system .................................................................................................................................... 53
Document feeder simplex operation ................................................................................................ 53
Fax functions and operation (fax models only) .................................................................................................. 54
Computer and network security features ......................................................................................... 54
PSTN operation .................................................................................................................................. 54
Receive faxes when you hear fax tones ............................................................................................ 54
Distinctive ring function .................................................................................................................... 55
Set up the distinctive ring function ................................................................................ 55
Fax by using voice over IP (VOIP) services ........................................................................................ 55
The fax subsystem ............................................................................................................................ 56
Fax card in the fax subsystem ........................................................................................................... 56
Safety isolation ............................................................................................................... 56
Safety-protection circuitry ............................................................................................. 56
Data path ......................................................................................................................... 56
Hook state ....................................................................................................................... 57
Downstream device detection ........................................................................................ 57
Hook switch control ........................................................................................................ 57
Ring detect ...................................................................................................................... 57
Line current control ......................................................................................................... 57
Billing or metering tone lters ....................................................................................... 58
Fax page storage in ash memory .................................................................................................... 58
Stored fax pages ............................................................................................................. 58
Advantages of ash memory storage ............................................................................ 58
2 Solve problems ............................................................................................................................................ 59
For additional service and support ...................................................................................................................... 60
Troubleshooting process ..................................................................................................................................... 61
Solve problems checklist ................................................................................................................... 61
Print the menu map ........................................................................................................ 62
Print a conguration page .............................................................................................. 62
Print the service page (includes the event log) .............................................................. 63
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Determine the problem source ......................................................................................................... 63
Pre-troubleshooting checklist ........................................................................................ 63
Troubleshooting owchart ............................................................................................. 64
Power subsystem .............................................................................................................................. 65
Power-on checks ............................................................................................................. 65
Power-on troubleshooting overview ........................................................... 66
Control panel checks ......................................................................................................................... 69
Tools for troubleshooting .................................................................................................................................... 71
Individual component diagnostics .................................................................................................... 71
Tools for troubleshooting: LED diagnostics ................................................................... 71
Network port LEDs ....................................................................................... 71
Two-line control panel LEDs ........................................................................ 72
Tools for troubleshooting: Engine diagnostics .............................................................. 72
Engine test .................................................................................................... 72
Diagrams ........................................................................................................................................... 73
Diagrams: Block diagrams .............................................................................................. 73
Sensors and switches (printer base) ............................................................ 73
Diagrams: Printed circuit assembly (PCA) connector locations ..................................... 75
Diagrams: Formatter connections ............................................................... 75
Diagrams: Engine controller PCA connections ............................................. 78
Diagrams: 550-sheet paper feeder controller PCA connections ................. 80
Diagrams: External plug and port locations ................................................................... 81
Diagrams: Locations of major components ................................................................... 82
Major components (printer base) ................................................................. 82
Motors (printer base) .................................................................................... 83
Fans (printer base) ........................................................................................ 83
Rollers and power switch (printer base) ...................................................... 84
PCAs (printer base) ....................................................................................... 85
Major components (550-sheet paper feeder) .............................................. 86
PCA (550-sheet paper feeder) ...................................................................... 86
Motors and rollers (550-sheet paper feeder) .............................................. 87
Diagrams: Timing chart .................................................................................................. 88
Diagrams: Circuit diagrams ............................................................................................. 89
Advanced conguration with HP Embedded Web Server (EWS) and HP Device Toolbox
(Windows) .......................................................................................................................................... 90
Control panel menus ......................................................................................................................... 93
2-line control-panel view (M452nw and M452dn models) ............................................ 93
Touchscreen control-panel view (M452dw model) ........................................................ 94
Home screen layout ...................................................................................... 95
Touchscreen control-panel view (M377, M477 models) ................................................ 96
Home screen layout ...................................................................................... 97
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Setup menu ..................................................................................................................... 97
HP Web Services menu ................................................................................. 98
Reports menu ............................................................................................... 99
Self Diagnostics menu ................................................................................ 101
Fax Setup menu (M477 models) ................................................................ 101
System Setup menu ................................................................................... 104
Service menu .............................................................................................. 109
Network Setup menu ................................................................................. 111
Quick Forms menu ...................................................................................... 112
Function specic menus ............................................................................................... 113
USB menu ................................................................................................... 113
Fax Menu (M477 models only) ................................................................... 113
Copy menu (M377, M477 models only) ...................................................... 115
Scan menu (M377, M477 models only) ...................................................... 117
Apps ............................................................................................................ 117
Jobs ............................................................................................................. 117
Supplies Status ........................................................................................... 117
Control panel message document (CPMD) ..................................................................................... 118
Control-panel message types ...................................................................................... 118
Control-panel messages and event log entries ........................................................... 118
30.XX Error Messages ................................................................................ 118
49.XX.YY Error Messages ............................................................................ 118
50.XX fuser errors ...................................................................................... 119
51.XX and 52 Laser/Scanner Errors ........................................................... 120
54.XX Error Messages ................................................................................ 121
55.XXXX Error Messages ............................................................................ 122
57.XX Error Messages ................................................................................ 123
58.XX Error Messages ................................................................................ 123
59.XX Error Messages ................................................................................ 124
79 Errors ..................................................................................................... 125
Alpha Error Messages ................................................................................. 126
Tools for troubleshooting: Event log messages .......................................................... 141
Print an error log ........................................................................................ 141
View the event log ...................................................................................... 141
Event-log messages ................................................................................... 142
Solve image quality problems ........................................................................................................................... 148
Improve print quality ...................................................................................................................... 148
Print from a dierent software program ..................................................................... 148
Check the paper-type setting for the print job ............................................................ 148
Check the paper type setting (Windows) ................................................... 148
Check the paper type setting (Mac OS X) ................................................... 149
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Check toner-cartridge status ....................................................................................... 149
Print and interpret the print quality page .................................................................... 150
Clean the printer ........................................................................................................... 150
Print a cleaning page .................................................................................. 150
Clean the scanner glass strip and platen ................................................... 151
Visually inspect the toner cartridge ............................................................................. 151
Check paper and the printing environment .................................................................. 151
Step one: Use paper that meets HP specications .................................... 151
Step two: Check the environment .............................................................. 151
Calibrate the printer to align the colors ....................................................................... 152
Check other print job settings ...................................................................................... 152
Check the EconoMode settings .................................................................. 152
Adjust color settings (Windows) ................................................................ 153
Try a dierent print driver ............................................................................................ 154
Print quality troubleshooting guide ................................................................................................ 155
Repetitive defects ruler ................................................................................................ 155
Use a ruler to measure between repetitive defects .................................. 156
Clean the printer ................................................................................................................................................ 160
Print a cleaning page ....................................................................................................................... 160
Clean the scanner glass strip and platen ........................................................................................ 160
Clean the pickup and separation rollers ......................................................................................... 161
Clean the pickup rollers and separation pad in the document feeder ........................................... 162
Clean the touchscreen ..................................................................................................................... 163
Solve paper-handling problems ........................................................................................................................ 164
Printer feeds incorrect page size .................................................................................................... 164
Printer pulls from incorrect tray ..................................................................................................... 164
Printer will not duplex or duplexes incorrectly ............................................................................... 164
Paper does not feed from Tray 2 .................................................................................................... 165
Output is curled or wrinkled ............................................................................................................ 165
Printer does not pick up paper or misfeeds .................................................................................... 166
The printer does not pick up paper .............................................................................. 166
The printer picks up multiple sheets of paper ............................................................. 166
The document feeder jams, skews, or picks up multiple sheets of paper (M377,
M477 models) ............................................................................................................... 167
Paper does not feed automatically .............................................................................. 167
Prevent paper jams ............................................................................................................................................ 168
Clear paper jams ................................................................................................................................................ 169
Introduction ..................................................................................................................................... 169
Experiencing frequent or recurring paper jams? ............................................................................ 169
Paper jam locations ......................................................................................................................... 170
Clear paper jams in the document feeder (M377, M477 models only) .......................................... 172
xii ENWW
Clear paper jams in Tray 1 ............................................................................................................... 174
Clear paper jams in Tray 2 ............................................................................................................... 177
Clear paper jams in the rear door and the fuser area (simplex models) ........................................ 178
Clear paper jams in the output bin .................................................................................................. 180
Clear paper jams in the duplexer (duplex models) ......................................................................... 181
Solve performance problems ............................................................................................................................ 182
Solve connectivity problems ............................................................................................................................. 183
Solve USB connection problems ..................................................................................................... 183
Solve wired network problems ....................................................................................................... 183
Introduction .................................................................................................................. 183
Poor physical connection .............................................................................................. 183
The computer is using the incorrect IP address for the printer ................................... 183
The computer is unable to communicate with the printer ........................................... 184
The printer is using incorrect link and duplex settings for the network ..................... 184
New software programs might be causing compatibility problems ........................... 184
The computer or workstation might be set up incorrectly .......................................... 184
The printer is disabled, or other network settings are incorrect ................................. 184
Solve wireless network problems ................................................................................................... 184
Introduction .................................................................................................................. 184
Wireless connectivity checklist ..................................................................................... 185
The printer does not print after the wireless conguration completes ...................... 185
The printer does not print, and the computer has a third-party rewall installed ..... 186
The wireless connection does not work after moving the wireless router or printer . 186
Cannot connect more computers to the wireless printer ............................................ 186
The wireless printer loses communication when connected to a VPN ........................ 186
The network does not appear in the wireless networks list ........................................ 186
The wireless network is not functioning ...................................................................... 186
Perform a wireless network diagnostic test ................................................................ 187
Reduce interference on a wireless network ................................................................. 187
Service mode functions ..................................................................................................................................... 188
Service menu ................................................................................................................................... 188
Secondary service menu ................................................................................................................. 189
Printer resets ................................................................................................................................... 191
Restore the factory-set defaults .................................................................................. 191
NVRAM initialization ..................................................................................................... 191
Super NVRAM initialization ........................................................................................... 191
Solve fax problems (fax models only) ............................................................................................................... 193
Checklist for solving fax problems .................................................................................................. 193
Perform a fax diagnostic test ......................................................................................................... 194
Solve general fax problems ............................................................................................................ 194
Faxes are sending slowly .............................................................................................. 194
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Print quality of a photo is poor or prints as a gray box. ............................................... 195
Fax quality is poor ......................................................................................................... 195
You touched the Cancel button to cancel a fax, but the fax was still sent ............. 196
No fax address book button displays ........................................................................... 196
Not able to locate the fax settings in HP Web Jetadmin .............................................. 196
The header is appended to the top of the page when the overlay option is enabled . 196
A mix of names and numbers is in the recipients box .................................................. 196
A one-page fax prints as two pages ............................................................................. 197
A document stops in the document feeder in the middle of faxing ............................ 197
The volume for sounds coming from the fax accessory is too high or too low ........... 197
Use fax over VoIP networks .......................................................................................... 197
Solve problems receiving faxes ...................................................................................................... 197
Solve problems sending faxes ........................................................................................................ 202
Fax error messages on the control panel ....................................................................................... 203
The No Fax Detected message displays ....................................................................... 203
The Communication error message appears ............................................................... 203
No Dial Tone .................................................................................................................. 204
The Fax is busy message appears ................................................................................ 205
The No fax answer message appears ........................................................................... 205
Document feeder paper jam ......................................................................................... 206
The Fax storage is full message appears ..................................................................... 206
Scanner error ................................................................................................................ 206
The control panel displays a Ready message with no attempt to send the fax .......... 206
The control panel displays the message "Storing page 1" and does not progress
beyond that message ................................................................................................... 206
Faxes can be received, but not sent ............................................................................. 207
Printer is password protected ...................................................................................... 207
Unable to use fax functions from the control panel .................................................... 207
Unable to use speed dials ............................................................................................. 207
Unable to use group dials ............................................................................................. 208
Receive a recorded error message from the phone company when trying to send
a fax ............................................................................................................................... 208
Unable to send a fax when a phone is connected to the printer .................................. 209
Troubleshoot fax codes and trace reports ...................................................................................... 209
View and interpret fax error codes ............................................................................... 209
Fax trace report ............................................................................................................ 210
Fax logs and reports ........................................................................................................................ 210
Print all fax reports ....................................................................................................... 210
Print individual fax reports ........................................................................................... 210
Set the fax error report ................................................................................................. 211
Set the fax-error-correction mode ................................................................................................. 211
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Change the fax speed ...................................................................................................................... 211
Use fax on a DSL, PBX, or ISDN system ........................................................................................... 212
DSL ................................................................................................................................ 212
PBX ................................................................................................................................ 212
ISDN ............................................................................................................................... 212
Solve email problems ........................................................................................................................................ 213
Cannot connect to the email server ................................................................................................ 213
Validate the SMTP gateway (Windows) .......................................................................................... 213
Validate the LDAP gateway (Windows) ........................................................................................... 213
Update the rmware ......................................................................................................................................... 214
Method one: Update the rmware using the control panel ........................................................... 214
Method two: Update the rmware using the Firmware Update Utility .......................................... 215
Appendix A Certicates of volatility ............................................................................................................... 217
Certicates of volatility ..................................................................................................................................... 218
Index ........................................................................................................................................................... 225
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xvi ENWW
List of tables
Table 1-1 Sequence of operation .......................................................................................................................................... 4
Table 1-2 Printer electrical components ............................................................................................................................ 13
Table 1-3 Motors1 ................................................................................................................................................................ 16
Table 1-4 Fans ..................................................................................................................................................................... 17
Table 1-5 Low-voltage power supply voltages .................................................................................................................. 18
Table 1-6 LVPS functions .................................................................................................................................................... 19
Table 1-7 Fuser control functions ...................................................................................................................................... 20
Table 1-8 Fuser control functions ...................................................................................................................................... 22
Table 1-9 Image-formation drive system .......................................................................................................................... 27
Table 1-10 Image-formation switch and sensor system ................................................................................................... 28
Table 1-11 Image formation process ................................................................................................................................. 29
Table 1-12 Toner cartridge control functions .................................................................................................................... 35
Table 1-13 Secondary transfer roller functions ................................................................................................................. 38
Table 1-14 Calibration functions ........................................................................................................................................ 40
Table 1-15 Photo sensors and switches ............................................................................................................................. 42
Table 1-16 Motors, clutches, and solenoids ....................................................................................................................... 43
Table 1-17 Print mode and feed speed .............................................................................................................................. 44
Table 1-18 Print mode and feed speed .............................................................................................................................. 45
Table 1-19 Tray 3 paper feeder electrical components ..................................................................................................... 49
Table 1-20 Tray 3 motor control ......................................................................................................................................... 49
Table 1-21 Pickup feed components (1x550-sheet paper feeder) .................................................................................... 50
Table 2-1 Troubleshooting owchart ................................................................................................................................. 65
Table 2-2 Formatter connections—M452nw/dn models ................................................................................................... 75
Table 2-3 Formatter connections—M452dw model .......................................................................................................... 76
Table 2-4 Formatter connections—M377, M477 models .................................................................................................. 76
Table 2-5 Engine controller PCA connectors ...................................................................................................................... 78
Table 2-6 550-sheet paper feeder controller PCA connectors .......................................................................................... 80
Table 2-7 Major components (printer base) ....................................................................................................................... 82
Table 2-8 Motors (printer base) .......................................................................................................................................... 83
Table 2-9 Fans (printer base) .............................................................................................................................................. 83
Table 2-10 Rollers and power switch (printer base) .......................................................................................................... 84
Table 2-11 PCAs (printer base) ........................................................................................................................................... 85
ENWW xvii
Table 2-12 Major components (550-sheet paper feeder) .................................................................................................. 86
Table 2-13 PCA (550-sheet paper feeder) .......................................................................................................................... 86
Table 2-14 Motors and rollers (550-sheet paper feeder) .................................................................................................. 87
Table 2-15 HP Web Services menu ..................................................................................................................................... 98
Table 2-16 Reports menu ................................................................................................................................................... 99
Table 2-17 Self Diagnostics menu .................................................................................................................................... 101
Table 2-18 Fax Setup menu .............................................................................................................................................. 101
Table 2-19 System Setup menu ....................................................................................................................................... 104
Table 2-20 Service menu .................................................................................................................................................. 109
Table 2-21 Network Setup menu ..................................................................................................................................... 111
Table 2-22 Quick Forms menu .......................................................................................................................................... 112
Table 2-23 USB menu ....................................................................................................................................................... 113
Table 2-24 Fax Menu ......................................................................................................................................................... 113
Table 2-25 Copy menu ...................................................................................................................................................... 115
Table 2-26 Scan menu ...................................................................................................................................................... 117
Table 2-27 Event-log messages (X=0: black cartridge, X=1: cyan cartridge, X=2: magenta cartridge, X=3: yellow
cartridge) .............................................................................................................................................................................. 142
Table 2-28 Fax event log codes ........................................................................................................................................ 147
Table 2-29 Repetitive image defects ............................................................................................................................... 155
Table 2-30 Solve performance problems ......................................................................................................................... 182
Table 2-31 Service menu .................................................................................................................................................. 188
Table 2-32 Secondary service menu ................................................................................................................................ 189
Table 2-33 Solve problems receiving faxes ..................................................................................................................... 197
Table 2-34 Solve problems sending faxes ....................................................................................................................... 202
xviii ENWW
List of gures
Figure 1-1 Relationship between the main printer systems ............................................................................................... 3
Figure 1-2 Engine-control system ...................................................................................................................................... 11
Figure 1-3 Engine-control unit ........................................................................................................................................... 12
Figure 1-4 High-voltage power supply ............................................................................................................................... 15
Figure 1-5 Low-voltage power-supply circuit .................................................................................................................... 18
Figure 1-6 Fuser control ..................................................................................................................................................... 20
Figure 1-7 Fuser control block diagram ............................................................................................................................. 21
Figure 1-8 Laser/scanner system ....................................................................................................................................... 23
Figure 1-9 Image-formation system block diagram .......................................................................................................... 25
Figure 1-10 Image-formation drive system ....................................................................................................................... 27
Figure 1-11 Image-formation switch and sensor system ................................................................................................. 28
Figure 1-12 Image-formation process ............................................................................................................................... 29
Figure 1-13 Primary charging ............................................................................................................................................. 30
Figure 1-14 Laser-beam exposure ..................................................................................................................................... 31
Figure 1-15 Development ................................................................................................................................................... 31
Figure 1-16 Primary transfer .............................................................................................................................................. 32
Figure 1-17 Secondary transfer ......................................................................................................................................... 32
Figure 1-18 Separation ....................................................................................................................................................... 33
Figure 1-19 Fusing .............................................................................................................................................................. 33
Figure 1-20 Drum cleaning ................................................................................................................................................. 34
Figure 1-21 Toner cartridge block diagram ........................................................................................................................ 35
Figure 1-22 ITB unit ............................................................................................................................................................ 38
Figure 1-23 Engine pickup, feed, and delivery system ...................................................................................................... 41
Figure 1-24 Photo sensors and switches ........................................................................................................................... 42
Figure 1-25 Motors, clutches, and solenoids ..................................................................................................................... 43
Figure 1-26 Jam detection sensors .................................................................................................................................... 47
Figure 1-27 550-sheet paper feeder .................................................................................................................................. 48
Figure 1-28 Tray 3 paper feeder controller ........................................................................................................................ 49
Figure 1-29 Paper pickup and feed operation (550-sheet paper feeder) ......................................................................... 50
Figure 1-30 Jam detection sensors (Tray 3) ....................................................................................................................... 51
Figure 2-1 Engine test page ................................................................................................................................................ 66
Figure 2-2 Engine test page ................................................................................................................................................ 67
ENWW xix
Figure 2-3 Engine test page ................................................................................................................................................ 69
Figure 2-4 Engine test page ................................................................................................................................................ 72
Figure 2-5 Sensors and switches (printer base) ................................................................................................................. 73
Figure 2-6 Sensors and switches (550-sheet paper feeder) ............................................................................................. 74
Figure 2-7 Formatter connections—M452nw/dn models ................................................................................................. 75
Figure 2-8 Formatter connections—M452dw model ........................................................................................................ 76
Figure 2-9 Formatter connections—M377, M477 models ................................................................................................ 76
Figure 2-10 Engine controller PCA connectors .................................................................................................................. 78
Figure 2-11 550-sheet paper feeder controller PCA connectors ....................................................................................... 80
Figure 2-12 Major components (printer base) ................................................................................................................... 82
Figure 2-13 Motors (printer base) ...................................................................................................................................... 83
Figure 2-14 Fans (printer base) .......................................................................................................................................... 83
Figure 2-15 Rollers and power switch (printer base) ......................................................................................................... 84
Figure 2-16 PCAs (printer base) .......................................................................................................................................... 85
Figure 2-17 Major components (550-sheet paper feeder) ................................................................................................ 86
Figure 2-18 PCA (550-sheet paper feeder) ........................................................................................................................ 86
Figure 2-19 Motors and rollers (550-sheet paper feeder) ................................................................................................. 87
Figure 2-20 General timing chart ....................................................................................................................................... 88
Figure 2-21 General circuit diagram (printer base) ............................................................................................................ 89
Figure 2-22 Print quality page ......................................................................................................................................... 150
Figure 2-23 Examples of repetitive defects ..................................................................................................................... 157
Figure 2-24 Place the ruler on the page ........................................................................................................................... 158
Figure 2-25 Locate the next repetitive defect ................................................................................................................. 158
Figure 2-26 Determine the defective assembly ............................................................................................................... 159
Figure A-1 Certicate of volatility M377 (1 of 2) .............................................................................................................. 218
Figure A-2 Certicate of volatility M377 (2 of 2) .............................................................................................................. 219
Figure A-3 Certicate of volatility M452 (1 of 2) .............................................................................................................. 220
Figure A-4 Certicate of volatility M452 (2 of 2) .............................................................................................................. 221
Figure A-5 Certicate of volatility M477 (1 of 2) .............................................................................................................. 222
Figure A-6 Certicate of volatility M477 (2 of 2) .............................................................................................................. 223
xx ENWW
1 Theory of operation
●
For additional service and support information
●
Basic operation
●
Formatter-control system
●
Engine-control system
●
Engine laser/scanner system
●
Engine pickup, feed, and delivery system
●
Input accessories
●
Scanning and image capture system
●
Document feeder system
●
Fax functions and operation (fax models only)
ENWW 1
For additional service and support information
HP service personnel, go to the Service Access Work Bench (SAW) at http://h41302.www4.hp.com/km/saw/
home.do.
Channel partners, go to HP Channel Services Network (CSN) at https://h30125.www3.hp.com/hpcsn.
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To access HP PartSurfer information from any mobile device, go to http://partsurfermobile.hp.com/ or
scan the Quick Response (QR) code below.
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Install and congure
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Printer specications
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Up-to-date control panel message (CPMD) troubleshooting
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Solutions for printer issues and emerging issues
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Remove and replace part instructions and videos
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Service advisories
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Warranty and regulatory information
2 Chapter 1 Theory of operation ENWW
Basic operation
Laser scanner system
Image-formation system
Pickup, feed and delivery system
Accessory
Scanner system
Formatter
Engine-control system
DC controller
Low-voltage power supply
High-voltage power supply
Fuser control
Engine-control unit
(M377 and M477 models only)
The printer routes all high-level processes through the formatter, which stores font information, processes
the print image, and communicates with the host computer.
The basic printer operation comprises the following systems:
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Engine control system
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Laser scanner system
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Image-formation system
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Pickup, feed, and delivery system
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Accessory (optional paper feeder)
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Integrated scanner system (M377, M477 models only)
Figure 1-1 Relationship between the main printer systems
ENWW Basic operation 3
Sequence of operation
The DC controller PCA controls the operating sequence, as described in the following table.
Table 1-1 Sequence of operation
Period Duration Description
Waiting From the time the power is turned on, the door is
closed, or when the printer exits sleep mode until the
printer is ready for printing.
Standby From the end of the waiting sequence, the last
rotation until the formatter receives a print command,
or until the printer is turned o.
Initial rotation From the time the formatter receives a print command
until the paper enters the paper path.
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Heats the fuser roller in the fuser
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Pressurizes the fuser lm
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Detects the toner cartridges
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Separates all of the developing rollers from the
photosensitive drums in the toner cartridges
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Rotates and stops each motor
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Cleans the intermediate transfer belt (ITB) and
secondary transfer roller
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Detects cable breakage on the thermistor
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Rotates and stops each fan
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Detects any residual paper in the engine
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Is in the Ready state
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Enters Sleep mode if the formatter sends the
sleep command
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The printer calibrates if it is time for an
automatic calibration
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Rotates each motor
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Rotates each fan
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Activates the high-voltage power supply
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Prepares the laser/scanner unit
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Warms the fuser to the correct temperature
4 Chapter 1 Theory of operation ENWW
Table 1-1 Sequence of operation (continued)
Period Duration Description
Printing From the time the rst sheet of paper enters the paper
path until the last sheet has passed through the fuser.
Last rotation From the time the last sheet of paper exits the fuser
until the motors stop rotating.
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Forms the image on the photosensitive drums
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Transfers the toner to the paper
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Fuses the toner image onto the paper
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Moves the last printed sheet into the output bin
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Stops each motor
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Stops the high-voltage power supply
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Stops the laser/scanner unit
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Turns the fuser heater o
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Cleans the ITB and secondary transfer roller
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If another print command is received, the printer
enters the initial rotation period when the last
rotation is complete.
ENWW Basic operation 5
Formatter-control system
The formatter performs the following functions:
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Controlling the sleep delay function
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Receiving and processing print data from the various printer inputs
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Monitoring control-panel functions and relaying printer status information (through the control panel
and the bidirectional input/output)
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Developing and coordinating data placement and timing with the DC controller PCA
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Stores font information
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Communicates with the host computer through the network or the bidirectional interface
The formatter receives a print job from the network or bidirectional interface and separates it into image
information and instructions that control the printing process. The DC controller PCA synchronizes the image
formation system with the paper input and output systems, and then signals the formatter to send the print
image data.
Sleep delay
When the printer is in sleep delay mode, the control-panel backlight is turned o, but the printer retains all
printer settings, downloaded fonts, and macros. The default setting is a 15-minute idle time. The setting can
be changed or turned o from the control panel menus.
The printer exits sleep delay mode and enters the warm-up cycle when any of the following occurs.
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A print job, valid data, or a PML or PJL command is received at the serial port.
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The control panel is touched (button press or touchscreen touch depending on model).
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A document is loaded in the document feeder or the scanner lid is opened (M377, M477 only).
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A tray is opened.
TIP: Error messages override the sleep delay message. The printer enters sleep mode at the appropriate
time, but the error message continues to appear.
Auto On / Auto O mode
2-line control panels
1. On the product control panel, press the OK button.
2. Open the following menus:
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System Setup
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Energy Settings
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Sleep/Auto O After
3. Use the arrow keys to select the time for the Sleep/Auto O delay, and then press the OK button.
6 Chapter 1 Theory of operation ENWW
Touchscreen control panels
1. From the Home screen on the product control panel, touch the Setup button.
2. Open the following menus:
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System Setup
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Energy Settings
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Sleep/Auto O After
3. Select the time for the Sleep/Auto O delay.
Printer job language (PJL)
PJL is an integral part of printer conguration, in addition to the standard PCL and PostScript (PS). With
standard cabling, the printer can use PJL to perform a variety of functions.
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Dynamic I/O switching: The printer can be congured with a host on each I/O by using dynamic I/O
switching. Even when the printer is oine, it can receive data from more than one I/O simultaneously,
until the I/O buer is full.
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Context-sensitive switching: The printer can automatically recognize the personality (PS or PCL) of
each job and congure itself to serve that personality.
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Isolation of print environment settings from one print job to the next: For example, if a print job is
sent to the printer in landscape mode, the subsequent print jobs print in landscape only if they are
formatted for landscape printing.
Printer management language (PML)
PML allows remote conguration of the printer and status monitoring through the input/output (I/O) ports.
Control panel
The formatter sends and receives printer status and command data to and from the control panel.
ENWW Formatter-control system 7
Walk-up USB
NOTE: Touchscreen models only.
This printer features printing from a USB ash drive. This printer supports printing the following types of les
from the USB ash drive.
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.pdf
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.jpg
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.prn and .PRN
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.cht and .CHT
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.pxl
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.pcl and .PCL
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ps and .PS
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doc and .docx
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.ppt and .pptx
When a USB ash drive is inserted into the front of the printer, the control panel will display the USB Flash
Drive menu. The les present on the USB ash drive can be accessed from the control panel.
Any les in a supported format on the USB ash drive can be printed directly from the printer control panel.
Pages also can be scanned and saved to the USB ash drive from the control panel.
Wireless
NOTE: Wireless models only.
Wireless products contain a wireless card to enable 802.11b/g/n wireless communication.
Low end data model (LEDM) overview
The low-end data model (LEDM) provides one consistent data representation method and denes the
dynamic and capabilities tickets shared between clients and devices, as well as the access protocol, event,
security, and discovery methods.
Advanced control language (ACL) overview
The advanced control language (ACL) is a language that supports printer control and rmware downloads in
printers that support both PJL/PCL and host-based printing. Each sequence of ACL commands must be
preceded by a unied exit command (UEL) and an @PJL ENTER LANGUAGE=ACL command. The ACL sequence
is always followed by a UEL. Any number of commands can be placed between the UELs. The only exception to
these rules is the download command. If a rmware download is done, the download command must be the
last command in the sequence. It will not be followed by a UEL.
The rmware searches for the UEL sequence when parsing commands. However, while downloading binary
data such as host-based code or NVRAM data the rmware suspends UEL parsing. To handle hosts that
8 Chapter 1 Theory of operation ENWW
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