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ITB unit contact/separation unit

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Figure 5-18 Secondary transfer roller unit ITB unit contact/separation unit Normally, the intermediate transfer belt is separated from the photosensitive drum. This operation presses the belt against the drum by moving the ITB unit contact lever at the beginning of print operation. When the fusing unit temperature reaches the print temperature at the beginning of the print operation, the DC controller turns the ITB unit contact/separation clutch (CL2) on. Once the ITB contact/separation clutch is on, the ITB unit contact/separation cam pushes on the ITB contact/ separation lever. This causes the lever to lift up on the ITB until it comes into contact with the photosensitive drum. The ITB will stay engaged with the drum throughout the transfer process. Once the entire print job is complete and CL3 and CL4 have been deactivated, the DC controller turns CL2 off and the ITB is lowered away from the photosensitive drum. 116 Theory of operation C7085-90921

Section	Page
Contents	7
List of Figures	9
List of Tables	13
Printer description	15
Printer features	16
Identification	20
Model and serial numbers	20
Power and regulatory information	21
Site requirements	22
Space requirements	23
Electrical specifications	24
Environmental specifications	24
Consumable storage requirements	25
Printer specifications	25
Printer assemblies	27
Media requirements	30
Selecting print media	30
Media specifications	30
Supported media weights and sizes	31
Non-supported media	32
Printing on special media	33
Environmental Product Stewardship Program	36
Regulatory statements	38
HP Color LaserJet 4500	38
HP Color LaserJet 4550	38
Safety information	39
Laser safety statement	39
Material Safety Data Sheet	39
Toner safety	39
Laser statement for Finland	40
Service approach	41
Service approach	42
Parts and supplies	43
Ordering parts	43
Ordering consumables	43
Exchange program	44
Consumables	44
World Wide Web	44
HP Service Parts Information Compact Disc	44
HP Support Assistant Compact Disc	44
Ordering related documentation and software	45
Warranty statement	46
Hewlett-Packard warranty statement	46
Onsite service agreements	47
Installation and configuration	49
Unpack the printer	50
Package contents	50
Installation	52
Using the parallel cable	60
Connecting to a network	66
Enhanced I/O (EIO) configuration	69
HP JetDirect print servers	69
LocalTalk I/O	70
CPU	70
Fast InfraRed Receiver (optional)	70
System requirements	70
Printer drivers	71
Network configuration	72
Configuring the printer for the network	72
Configuring Novell NetWare frame type parameters	72
Configuration tips	73
NetWare 3.x and 4.x based products	73
Windows 3.1, Windows 95, and Windows NT 3.51 and 4.0 networks	73
IBM OS/2 LAN Server and Warp Server networks	74
LocalTalk network	74
UNIX networks	74
Setting network security on the printer	75
Locking the control panel	76
Using an ASCII PJL escape sequence to set network security	77
Printer maintenance	79
Cleaning the printer and accessories	80
Cleaning spilled toner	80
Approximate replacement intervals for consumable items	82
Imaging drum life	82
Replacement intervals for consumables	85
Locating consumables	86
Replacing consumable items	87
DIMM configuration	100
Adding memory	100
Theory of operation	103
Introduction	104
Basic operation	105
Image formation	106
Primary charge	107
Laser exposure	108
Development	108
Transfer	109
Waste toner cleaning	111
Fusing	112
Toner density	113
Mechanical system	114
Photosensitive drum cartridge	114
Intermediate transfer belt	115
Toner carousel	120
Laser/scanner operation	122
Paper path	124
Introduction	124
Tray 2 (cassette)	125
Tray 1 (multi-purpose tray)	126
Tray 3 (500-sheet paper feeder)	128
Paper size detection	129
Fusing and delivery unit	129
Duplex unit paper path	130
DC controller subsystem	134
Motors and fans	135
Formatter system	137
Control panel	137
Power supplies	137
Power supply overview	137
High-voltage power supply	138
Removal and replacement	139
Introduction	141
Removal and replacement strategy	141
Repair notices	141
Caution regarding electrostatic discharge (ESD)	141
Determining the printer version	142
Required tools	142
Types of screws	143
Consumable assemblies	144
Covers, drawers, and top and front assemblies	146
Top cover	146
Left side cover	147
Right side cover	148
Rear door	149
Right rear cover	150
Drum drawer (top drawer) cover	151
ITB drawer (middle drawer) cover	153
ITB drawer (middle drawer)	154
Control panel	155
Installing or changing the control panel overlay	156
Front right cover	157
Radio Frequency Interference (RFI) shield	158
Laser/scanner assembly	159
DC controller	160
Developing PCB	161
Top cover switch assembly	163
Drum drawer (top drawer) assembly	165
Densitometer assembly	168
Right side assemblies	170
Formatter	170
Formatter PCB	171
Formatter pan assembly	172
Power supply	175
High-voltage power supply	176
Drum drive assembly	178
Large fan housing	180
Carousel drive assembly	181
Paper size switch PCB	183
Left side assemblies	184
Drawer switch assembly	184
Paper feed PCB	185
Fusing motor (M1)	187
Paper path pick-up motor (M2)	189
Paper pick solenoid (SL2)	190
ITB cleaning roller clutch (CL3)	191
ITB clutch (CL2) assembly	192
Transfer roller cam clutch (CL4)	194
Left side gears	195
Rear assemblies	197
Large right side fan	197
Left side fan	199
Face-down assembly	201
Internal assemblies	202
Cartridge carousel assembly	202
Toner catch tray and paper transport assembly	206
Paper pick rollers	207
Star wheel assembly	208
Transfer roller assembly	209
Cam shafts	210
Troubleshooting	211
Introduction	213
Troubleshooting process	214
Pre-troubleshooting checklist	214
Troubleshooting flowchart	215
Troubleshooting power-on	218
Printer error troubleshooting	219
Printer messages	219
Alphabetical printer error messages	219
Numerical printer error messages	228
Paper path troubleshooting	239
Jams	239
Jam locations	240
Jam locations by error message	241
General paper-path checklist	243
Print media checklist	243
Jam recovery	244
Image formation troubleshooting	245
Print density test and color checks	245
Understanding color variations	246
Color selection process	246
Customizing color output through printer drivers	246
HP ColorSmart II	248
Color management options	248
Matching colors	249
Four-color printing (CMYK)	250
Matching PANTONE® colors	250
Automatic PANTONE ® calibration	250
Adjusting color balance	252
Image defects	255
Background scatter	256
Banding and horizontal lines	256
Black lines	257
Black or partially black pages	257
Blank or white pages	258
Character voids	259
Colorless output (black only)	259
Distorted image	259
Dropouts	259
Faded print, faded areas, or faded vertical streaks	260
Full-page ghosting	260
Gray streaks	260
Irregular, raised spots or stray toner	261
Light, dark, or faded print	261
Light black or no black print	261
Loose toner	262
Mottled or marbled output	262
Random spots	262
Sharkskin (rough, mottled printing)	262
Single color missing	262
Sunburn	262
Toner smear	263
Vertical lines or streaks	263
Vertical black lines	263
Vertical white lines	263
Wavy characters	264
Overhead transparency defects	265
Dull or dark transparencies	265
Incorrect image on transparencies	265
Repetitive defects on transparencies	265
Streaking on transparencies	266
Repetitive defects troubleshooting	267
Imaging drum defects	267
Repetitive defect ruler	268
Interface troubleshooting	270
Communications checks	270
EIO troubleshooting	270
AUTOEXEC.BAT standard configurations	271
Printer Job Language (PJL) commands	271
Control panel troubleshooting	273
Control panel access	273
Printing a menu map	273
Information Menu	275
Paper Handling Menu	276
Configuration Menu	278
Printing Menu	280
I/O Menu	282
EIO Menu	282
Calibration Menu	283
Resets Menu	284
Hard disk dependent menus	285
Private/Stored Jobs menu	286
Troubleshooting tools	287
Embedded Web server	287
To use the embedded Web server	287
Embedded Web server page sets	287
Networking page set	289
Printer configuration page	289
Supplies status page	292
Interpreting the supplies status page	292
Usage page	293
Interpreting the usage page	293
Event log	294
Hard disk file directory page	294
Service mode	295
Accessing the service mode	295
Description of Service Menu items	298
Diagnostics mode	302
Entering diagnostics mode	302
Formatter diagnostics	302
Engine diagnostics	304
Engine test	308
NVRAM initialization	309
Diagrams	310
Parts and diagrams	325
Introduction	326
Ordering parts	327
Consumables, accessories, and supplies	327
Common fasteners	330
Illustrations and parts lists	331
Determining the printer version	331
Alphabetical parts list	357
Numerical parts list	361

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116

Theory of operation

C7085-90921

Figure

5-18

Secondary transfer roller unit

ITB unit contact/separation unit

Normally, the intermediate transfer belt is separated from the photosensitive drum. This operation

presses the belt against the drum by moving the ITB unit contact lever at the beginning of print

operation.

When the fusing unit temperature reaches the print temperature at the beginning of the print

operation, the DC controller turns the ITB unit contact/separation clutch (CL2) on. Once the ITB

contact/separation clutch is on, the ITB unit contact/separation cam pushes on the ITB contact/

separation lever. This causes the lever to lift up on the ITB until it comes into contact with the

photosensitive drum. The ITB will stay engaged with the drum throughout the transfer process.

Once the entire print job is complete and CL3 and CL4 have been deactivated, the DC controller

turns CL2 off and the ITB is lowered away from the photosensitive drum.