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HP 8550mfp Service Manual - Page 135

Theory of operation

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5 Theory of operation Chapter contents Introduction 135 Color theory 138 Subtractive color theory 138 Additive color theory 140 Image formation 141 Electrostatic latent image formation block 143 Developing block 145 Transfer block 146 Transfer drum cleaning block 150 Imaging drum cleaning block 152 Fusing block 153 Consumable detection mechanisms 154 Drum kit life detection 154 Transfer kit life detection 156 Color toner lever detection 158 Black toner level detection and cartridge detection . . 159 Environment change control 159 Color calibration density sensor 160 Transfer belt control 161 Cleaning roller control 162 Carousel control 162 EN Chapter contents 133

Section	Page
Table of Contents	5
List of Figures	9
List of Tables	17
Product information	21
Introduction	23
Printer features	24
Specifications	26
Electrical specifications	26
Operating environment specifications	26
Acoustic emission specifications	27
Printer dimensions	27
Consumable storage specifications	28
Site requirements	29
General guidelines	29
Space requirements	30
Media requirements	31
Selecting media	31
Storing media	32
Media capacity and sizes for input trays	33
Media capacity and sizes for the multi-bin mailbox	35
Printable area	36
Media considerations	37
Media to avoid	39
Identification (model and serial numbers)	40
Printer Information	41
Configurations	41
External views	43
Formatter assemblies	45
Media-handling accessories and options	46
Safety information	48
FCC regulations	48
Canadian DOC regulations	48
Declarations of conformity	49
VCCI statement (Japan)—8500 models	56
VCCI statement (Japan)—8550 models	56
EMI statement (Korea)—8500 models	56
EMI statement (Korea)—8550 models	56
Laser safety statement	57
Laser statement for Finland	58
Product information sheet	59
Toner safety	59
Material Safety Data Sheet (MSDS)	59
Ozone safety	60
Service approach	61
Introduction	63
Parts and supplies	63
Ordering	64
Obtaining related documentation and software	64
Ordering consumables	64
Ordering field-replaceable units	65
Parts exchange program	65
Technical assistance	66
List Server	66
HP ASAP	66
Dealer Response Line	67
HP Software Distribution Center	68
HP Direct	68
Customer Support Sales Center	68
Parts identification	68
Customer Information Centers	68
HP Customer Care Centers	69
Warranty	71
Installation	71
Toner cartridge information	71
Operational overview	73
Verifying package contents	75
Verifying the cables are installed	76
Printer with stand	76
Printer with a 2,000-sheet input unit	77
Connecting the printer to the network	78
Connecting to a 10Base-T or 100Base-TX network	79
Connecting to a 10Base2 network	79
Connecting to a LocalTalk network	79
Connecting a parallel cable	80
Changing the printer control panel overlay	81
Printer control panel layout	82
Menu maps	84
Information Menu	85
Proof and Print Menu (HP Color LaserJet 8500)	86
Quick Copy Jobs Menu (HP Color LaserJet 8550)	86
Private/Stored Jobs Menu (HP Color LaserJet 8550)	87
Paper Handling Menu	87
Configuration Menu	90
Printing Menu	91
Duplex Registration Menu (HP Color LaserJet 8550)	93
I/O Menu	93
Resets Menu	94
Color Adjust Menu	94
Service Mode Menu	95
Selecting the display language	99
Installing the consumables	100
Configuring input trays	105
Selecting the mode for tray 1	105
Configuring media type and size	106
Verifying the printer is installed correctly	107
Configuration page	107
EIO page	107
Verifying DIMM installation	108
Duplex registration (HP Color LaserJet 8550)	109
Booklet printing	111
HP TonerGauge (HP Color LaserJet 8550)	112
Resetting the HP TonerGauge	112
Printer maintenance	113
Cleaning procedures	115
Cleaning the post charger	115
Cleaning the density sensor	116
Cleaning the transfer charger	117
Cleaning the toner catch tray	118
Printer consumables	120
Replacement frequencies	121
Replacing consumables	122
Theory of operation	135
Introduction	137
Color theory	140
Subtractive color theory	140
Additive color theory	142
Image formation	143
Electrostatic latent image formation block	145
Developing block	147
Transfer block	148
Transfer drum cleaning block	152
Imaging drum cleaning block	154
Fusing block	155
Consumable detection mechanisms	156
Drum kit life detection	156
Transfer kit life detection	158
Fuser kit life detection	158
Color toner level detection	158
Color cartridge sensor	159
Color toner lever detection	160
Black toner level detection and cartridge detection	161
Environment change control	161
Color calibration density sensor	162
Transfer belt control	163
Cleaning roller control	164
Carousel control	164
Electrical systems	166
Power distribution	166
Fuser control	168
High-voltage power supply circuit	169
Mechanical systems	171
Laser/scanner	171
Motors and heaters	173
Paper path	180
Pick-up/feed	181
Sensors, switches, clutches, and solenoids	186
Fusing and delivery unit	192
Media jam detection	194
Printer timing	194
EPH controller board	201
Duplexer	201
2,000-sheet input unit	201
Power supply	201
Sensors, switches, clutches, and motors	202
Pick-up and feed system	203
Switch functionality	204
Lifter operation	205
Paper path	206
Multi-bin mailbox	207
Operating modes	207
Configuring operating modes	208
Power-on sequence	208
Communication link (C-link) cables	209
Sensors, switches, motors, and controller board PCA	210
Receiving paper	211
Delivering paper	211
Paper path	212
3,000-sheet stapler/stacker	213
Device configuration	213
Power supply	214
C-link communication	214
Paper path sensors and jam detection	215
Paper path	216
Removal and replacement	219
Introduction	224
Removal and replacement strategy	224
Repair notices	224
Electrostatic discharge (ESD)	224
Required tools	225
Maintenance units	226
Doors and covers	227
Front covers and panels	230
Top cover assembly	234
Left covers and doors	236
Right covers and doors	240
Rear cover	245
Top assemblies	247
Control panel	248
Laser/scanner unit	249
Face-down output assembly	251
Front assemblies	253
Toner lock sensor and color cartridge sensor	253
Subrelay PCA	254
Left assemblies	255
Multi-bin mailbox/3,000-sheet stapler/stacker/ 3,000-sheet stacker	255
Formatter board	256
Internal printer hard disk (DN model)	258
Feeder assembly	259
Face-up solenoid	260
Face-up exit assembly	262
Right assemblies	263
Tray 1	263
Pick-up roller	264
Registration roller assembly	265
Paper photo (OHT) sensors	267
Density sensor	268
Paper pick-up assembly	269
Tray 1 pick-up assembly	270
Rear assemblies	272
Formatter pan	274
Fan 1	276
Fan 2	277
Power supply	278
Controller board	279
ECO board	281
Cartridge motor (M3)	282
Main motor (M4)	283
Carousel motor PCA	284
Carousel motor (M1)	285
Delivery drive assembly	287
Main gear assembly (not shown)	289
Post charger HV module assemblies	290
Cleaning roller HV module assemblies	293
Main relay PCA	295
Drum/cartridge drive assembly	296
Separation discharge high-voltage converter assemblies	297
Tray 2 and tray 3 media-size sensing PCAs	298
2,000-sheet input unit	300
Front cover	301
Back cover	302
Left cover	303
Vertical transfer unit	304
Right cover	306
Tray 4	307
Paper pick-up assembly	308
Controller PCA	309
Front LED PCA assembly	310
Power supply	311
Main drive assembly	312
Paper-size sensor assemblies	313
Tension springs	315
Multi-bin mailbox	316
Front and back covers	317
Top cover	318
Power supply	319
Paper bins and blind cover	320
Flipper assembly	321
Delivery head position motor	323
Transport belt motor	324
Input paper guide	325
Metallic tape and housing assembly	327
Controller PCA	329
Anti-curl strings	331
Delivery head assembly	333
Interlock switch	336
Diagnostic LED PCA	337
User status LED PCA	338
Attachment assembly	339
3,000-sheet stapler/stacker and 3,000-sheet stacker	340
Bins and covers	341
Internal assemblies	345
Troubleshooting	365
Pre-troubleshooting checklist	369
Printer message troubleshooting	370
Aids to troubleshooting	417
Configuration page	417
Continuous configuration page	420
Demonstration page	420
Event log	421
Service mode engine diagnostics	422
Disabling interlocks	427
Service mode formatter diagnostics	432
Cold reset	433
Fault log	434
Paper path troubleshooting	435
General paper path checklist	435
Wrinkled pages	435
Sealed envelopes	436
Media jams	436
Image formation troubleshooting	440
Understanding color variations	441
Common causes of color variation	441
Image defects troubleshooting	443
Image orientation	443
Image defect examples	444
Toner cartridge manufacturing codes	458
Color balance adjustment	459
Repetitive defects troubleshooting	464
Repetitive defects troubleshooting	465
Color developer roller	466
Charging roller	466
Black developer roller	466
Cleaning roller	466
Developer DSD wheels	466
Transfer roller	467
Transfer drum	467
Fuser	469
Imaging drum	469
Transfer belt	470
2,000-sheet input unit troubleshooting	471
Ways to troubleshoot the unit	471
Status LED descriptions	472
Service LED descriptions	473
Standalone running test	475
Motor test	476
Sensor test	477
Multi-bin mailbox troubleshooting	479
Switching the multi-bin mailbox to test mode	479
Power-up sequence test	480
Paper path test	480
Multi-bin mailbox LED descriptions	481
3,000-sheet stapler/stacker troubleshooting	484
Calibrating the staple position	484
Troubleshooting tools	486
Printer messages	493
Communications troubleshooting	504
HP network interface support	504
Third-party network interface support	504
Diagrams	505
Parts and diagrams	511
Overview	513
Ordering parts	513
Consumables, options, and accessories	513
Miscellaneous parts	516
Illustrations and parts lists	518
Compatible parts	518
Major assembly locations	519
Printer covers and doors	521
Internal cover assembly	528
Internal components	530
Drum/cartridge drive assembly	542
Delivery drive assembly	543
Tray 3 assembly	544
Tray 2 assembly	545
Paper pick-up assembly	546
Registration frame assembly	550
Registration roller assembly	551
Feeder assembly	552
Tray 1 pick-up assembly	553
Tray 1 assembly	554
Delivery assembly	555
Delivery cover assembly	556
Transfer belt assembly	557
Fuser assembly	558
PCA assemblies	561
2,000-sheet input unit components	562
Multi-bin mailbox components	566
3,000-sheet stapler/stacker components	572
Numerical parts list	576
Alphabetical parts list	589
Index	603
Numerics	603
A	603
B	604
C	605
D	607
E	609
F	610
G	611
H	611
I	612
J	613
K	613
L	613
M	614
N	616
O	616
P	616
Q	619
R	619
S	620
T	622
U	625
V	625
W	625