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Dual-beam method,

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Dual-beam method The laser/scanner unit contains two laser diodes in the laser unit. The printer employs the "dualbeam method," which scans two lines simultaneously. Based on signals it receives from the DC controller and the formatter, the laser/scanner PCA in turn signals the two laser diodes to emit laser beams. The beams strike a four-sided mirror that rotates at a constant speed through the collimator lens and cylindrical lens. The beams reflect off of the mirror, pass through a focusing lens and a reflective mirror, and focus on the photosensitive drum. The scanning mirror, rotating at a constant speed, reflects the laser beams, which scan across the drum at a constant speed. Then, a latent image is formed on the drum surface by constant-speed rotation of the photosensitive drum and constant-speed scanning of the laser beams. First scan Second scan Third scan Fourth scan Feed direction LD1 scan line LD2 scan line Image area Figure 43. Dual-beam method ENWW Chapter 5 Theory of operation 161

Section	Page
Table of contents	5
List of figures	11
List of tables	19
Product information	23
Product features	24
HP Color LaserJet 9500n printer (C8546A)	24
HP Color LaserJet 9500hdn printer (C8547A)	24
HP Color LaserJet 9500mfp (C8549A)	24
Features of the HP color LaserJet 9500 series printer	25
Features of the HP Color LaserJet 9500mfp	26
Product specifications for the printer	27
Identification	27
Specifications	27
Environmental specifications	28
Product overviews	30
External assembly locations	30
Accessories	31
Space requirements	34
Printer with packaging	34
Physical dimensions of the printer models and the MFP	35
Printer setup	38
Media specifications	39
Guidelines for selecting media	39
Supported media and capacity for input and output	40
Recommended media	41
Ordering recommended media	41
Special media specifications	43
Envelope specifications	43
Envelopes with adhesive strips or multiple flaps	44
Label specifications	44
Card stock construction	45
Transparency specifications	45
Preprinted forms and special letterhead	45
Embossed media	46
Glossy media	46
Media with cutouts or perforations	46
Chemically treated media	46
Synthetic media	46
Other special media	47
Storing print media	47
Envelope storage	47
Testing media specifications	47
Basis weight field test	48
Metric sizes	48
Paper weight equivalence table	48
Caliper field test	50
Paper finish field test	50
Moisture content field test	50
Grain field test	50
Curl field test	51
Cut edge condition field test	51
Furnish (fiber composition) field test	51
Fusing compatibility field test	51
Media assessment tools and suppliers	52
Service approach	53
Service approach	54
Parts and supplies	55
Ordering parts	55
Ordering supplies	55
Exchange program	55
Supplies	55
World Wide Web	55
HP service parts information compact disc	56
Customer care reseller sales and service support center	56
HP authorized resellers and support	56
HP service agreements	56
Other areas	56
Ordering related documentation and software	57
Warranty	58
Limited warranty for print cartridge and image drum life	58
Transfer unit and fuser warranty	58
HP maintenance agreements	58
Onsite service agreements	59
Priority onsite service	59
Next-day onsite service	59
Weekly (volume) onsite service	59
Product configuration	61
Printer control panel layout	62
Control panel menus	64
Menu map	64
Using a menu map	64
Select an item from the menu map	64
Retrieve job menu	65
Information menu	66
Paper handling menu	67
Selecting media for a document	68
Configure device menu	69
Printing submenu	69
PCL submenu	71
Print Quality submenu	72
System Setup submenu	77
Output Setup submenu	79
I/O submenu	79
Parallel Input submenu	79
EIO submenu	80
Resets submenu	82
Diagnostics menu	83
Service menu	88
Service ID	88
Restoring the Service ID	89
Converting the Service ID to an actual date	89
Settings and defaults	90
Configure the control panel display language	90
To configure the control panel language (using menus)	90
To configure the control panel language (power-on sequence)	91
Configure the input trays	91
Configuring trays for standard size media	91
Configuring trays for custom size media	93
Printable area	95
Boot key sequences	96
Hard disk reinitialization	96
Reinitialize a hard disk using the control panel	96
Reinitialize a hard disk using PJL commands	96
NVRAM initialization	97
To initialize NVRAM	97
Cold reset	99
To skip disk	99
To skip calibration	99
Product maintenance	101
Preventative maintenance	102
Image transfer kit	102
Storing the image transfer kit	102
Image cleaning kit	102
Image fuser kit	103
Cleaning the printer and accessories	104
General cleaning	104
Cleaning spilled toner	104
Vacuum specifications	104
First aid measures	105
Cleaning procedures	106
Cleaning the post charger	106
Cleaning the separation guide, feed guide, and front fuser guide	106
Cleaning the fuser input	106
Cleaning the registration roller unit	107
Cleaning the other rollers	107
Cleaning the tray 1 separation pad	107
Print cartridges	108
Non-HP print cartridges and image drums	108
Authenticating print cartridges	108
Storing print cartridges	109
Image drums	110
Storing image drums	110
Handling instructions	110
Firmware upgrades to the printer or MFP	111
Downloading the new firmware from the HP Web site	111
Downloading the new firmware to the printer	111
Remote firmware update through a local Windows® port	112
Windows 95, Windows 98, or Windows Me	112
Windows NT® 4.0, Windows 2000, Windows XP, or Windows Server 2003	112
Remote firmware update through a Windows network	113
Remote firmware update for UNIX® systems	113
Remote firmware update using FTP on a direct network connection	113
Windows operating systems	113
Mac operating systems	115
Remote firmware update using FTP through a browser	115
Remote firmware update using Fetch (Mac OS 8.6 and OS 9. x only)	116
Remote firmware update using the HP LaserJet utility (Mac OS 8.6 and OS 9. x only)	116
Remote firmware update using the LPR command	117
Using HP Web Jetadmin to download the firmware to the printer of MFP	117
Messages during the firmware update	118
Troubleshooting a firmware update	118
Theory of operation	121
Basic operation	122
Major printer systems	122
Printer block diagram	123
Sequence of operation	124
Timing charts	126
Wiring diagrams	128
Flat flexible cable signals	132
Connector location	140
Engine-control system	144
DC controller circuit	145
DC controller operations	148
T driver circuit	149
Fuser control circuit	150
Low-voltage power supply	151
High-voltage power supply circuits	152
Post charger power supply unit	152
Motors and fans	153
Switches, solenoids, clutches, and sensors	156
Formatter	160
Formatter heartbeat LED	161
DIMM slots	161
Laser/scanner system	162
Dual-beam method	163
Laser control	164
Laser diode automatic light emission control	165
Image mask control	166
Horizontal synchronous control	166
Laser failure detection	167
Scanner-motor control	168
Scanner-motor-speed control	168
Scanner motor failure detection	169
Color-plane registration calibration control	169
Image CPR adjustment	169
Laser-beam-skew calibration	171
Laser adjustment	171
Image formation system	172
Electrophotographic process	172
Step 1	173
Step 2	173
Step 3	174
Step 4	175
Step 5	176
Step 6	176
Step 7	177
Step 8	177
Step 9	178
Step 10	178
Step 11	179
Step 12	179
Image stabilization control	180
Environment calibration control	180
Image-density-detection control	181
Image-density-calibration control	182
Image-halftone-calibration control	182
Paper-path system	183
Pickup/feed unit	185
Cassette paper size detection/cassette paper detection	185
Cassette pickup	186
Tray 1 paper pickup	188
Paper pickup and feed	191
Jam detection	192
Tray 4 for the HP LaserJet 9500 Series printer	194
Tray 4 driver PCB	194
Power supply	194
Sequence of operation	195
Pickup and feed	195
Media level and size detection	195
Jam detection	195
Removal and replacement	197
Introduction	199
Removal and replacement strategy	199
General cautions during removal and replacement	199
Electrostatic discharge	200
Required tools	200
Flat flexible cable caution	201
To reinstall	201
DC controller and cable/connector damage areas	202
Potential damage areas while servicing	202
Consumables	203
Toner cartridges (print cartridges)	203
Process cartridges (image drums)	205
Waste toner bottle (toner collection bottle)	207
Transfer cleaner (cleaning blade)	208
Transfer roller	209
External covers	210
Control panel overlay	210
Control panel	211
To reinstall	211
Right upper cover	212
Left upper cover	214
Top right cover	215
To reinstall	216
Top left cover	217
To reinstall	218
Front doors	219
Fuser door	220
Intermediate transfer belt (ITB) door	222
Left back cover	226
Left lower cover	227
Right back cover	229
Back cover	230
Major assemblies	231
Process cartridge (image drum) door	231
Laser/scanner assembly	233
To reinstall	234
Printing a laser/scanner adjustment page	235
Reading a laser/scanner adjustment page	237
Overview	237
Adjusting the laser/scanner assemblies	239
Overview	239
Laser scanner adjustment step 1	240
Laser/scanner adjustment step 2	244
Delivery unit	251
Delivery unit sensor	255
To reinstall	255
Vertical feed unit	256
Duplexer	260
Fuser	261
Intermediate transfer belt (ITB)	262
Density and registration sensor assembly	264
Right back fan	267
Right front fan	268
Secondary transfer assembly (T2)	269
To reinstall	273
Pickup unit	274
Temperature and humidity sensor	282
To reinstall	282
High-voltage power supply	283
Low-voltage power supply	284
Registration assembly	285
To reinstall	291
Delivery fan	292
Fuser fan	293
P-crg (image drum) drive assembly	294
T-crg (print cartridge) drive assembly	298
Fuser motor	300
Fuser drive assembly	301
DC controller	302
To reinstall	303
Formatter PCB	304
Formatter cage	306
High-voltage contact	308
Post charger power supply	309
Tray 1 pickup roller	311
Tray 1 separation pad	312
Left door switch	313
Right door switch (front and right side doors)	314
ITB sensor	315
Upper left door sensor	316
Fuser front paper sensor	317
Fuser sensor PCA	318
2,000-sheet tray 4 for the HP LaserJet 9500hdn printer	319
Front and right side orientation	319
Back and left side orientation	319
Left side cover	320
To reinstall	320
Right side cover	321
To reinstall	321
Back covers	322
Center back cover	322
Right back cover	322
Left back cover	322
Tray 4	323
Rollers (pickup, feed, and separation)	324
To reinstall	324
Registration assembly	325
Drive motor	326
Drive assembly	326
Controller board	327
Paper-size detection switch PCB	328
To reinstall	328
Power supply	329
Pickup assembly	330
Paper connecting unit	331
Troubleshooting	333
Introduction	336
Troubleshooting process	336
Pre-troubleshooting checklist	336
Power checks	338
Control panel checks	338
Troubleshooting tools and procedures	339
Hardware and electrical troubleshooting tools	339
Engine diagnostic tools	339
Defeating interlocks	339
Engine diagnostics preconditions	340
Disable cartridge test	340
Paper-path test (and automatic sensors test)	340
Sensor test (interactive)	341
Components test	342
Component test: Transfer motors test	343
Component test: Belt only test	343
Component test: Image drum motors test	344
Component test: YMCK laser test	346
Component test: Tray 1 feed motor test	347
Component test: Tray 3 feed drive test	349
Component test: Pre-registration test	349
Component test: Face-up solenoid test	350
Print stop test	351
Engine-test button	352
Engine-test-print page	352
Formatter heartbeat LED	353
Information pages	354
Configuration page	354
Supplies status pages	356
Usage page	358
File directory page	359
Electrical connection and contact failures	360
Image-formation and print-quality troubleshooting tools	361
Print-quality problems associated with the environment	361
Print-quality problems associated with media	361
Reseating consumables	361
Cleaning the post charger	361
Cleaning the fuser input	361
Color band test	366
Engine test print page	366
Laser/scanner adjustment page	367
Door ruler and repeating defect frequencies	367
Sample defects and solutions	368
Repeating marks (98 mm)	369
Repeating marks (45 mm)	370
Lines and bands appear perpendicular to feed direction	373
Lines, streaks or scratches appear parallel to feed direction	376
Diagonal bands or lines	380
Light or faint image and dropouts	382
Wavy brush marks	386
Color plane misregistration	387
Primary color covers entire page	389
Ghosted image (98 mm)	390
Ghosted image (140 mm)	391
Distorted or misplaced image	393
Poorly fused image	394
Missing color plane	396
Blank	397
Hand or fingerprints	397
Fine, yellow dot background	399
Toner halos or explosions occur around solid secondary colors	400
Control panel print-quality adjustments	402
Print-quality problems associated with jams	404
Media and paper-path troubleshooting tools	405
Paper-path jam sensors	405
Determine the problem source: print media or printer	410
Using the straightest paper path	411
Determine if problem is caused by the duplexing process	411
Isolate the source of the jam	411
Determine where media jams occur	411
Determine whether the printer is experiencing misfeeds or multifeed jams	411
Print-quality problems associated with media	411
Isolate a media brand	412
Isolate a media type	412
Wrinkling envelopes	412
Poor fusing	412
Overhead transparency defects	413
Media jam	413
Customer print job	414
Clearing jams	414
Tests for troubleshooting paper-path problems	415
Print stop test	415
Paper-path test	415
Sensor test	415
Tray alignment adjustment	415
Noise-troubleshooting tools	416
Control panel messages for the HP LaserJet 9500 Series printer	417
Control panel and event log message format	418
Event log page	418
Print an event log	418
Show an event log	419
Interpret an event log	419
Sample event log page	420
Error message interpretation	421
Alphabetical error messages for the HP LaserJet 9500 Series printer	421
Numerical error messages for the HP LaserJet 9500 Series printer	433
Data and communication troubleshooting tools	468
Test message	468
EIO troubleshooting	468
Software/network troubleshooting	468
Jetdirect configuration	469
Verify network and server operation	469
Jetdirect page	470
Troubleshooting tools for the HP LaserJet 9500hdn printer tray 4	471
Tray 4 diagnostics label (LJ 9500)	471
Tray 4 motor test (LJ 9500)	471
Tray 4 standalone running test (LJ 9500)	471
Tray 4 sensor test (LJ 9500)	472
Tray 4 light pattern interpretation (LJ 9500)	473
Tray 4 does not print media (LJ 9500)	473
Parts and diagrams	475
Introduction	477
Ordering parts	477
Customer support information	477
Terminology	478
Unique parts	478
Kits, supplies, accessories, exchange parts, and documentation	481
Hardware identification	485
Illustrations and parts lists	486
External covers and panels	486
Left cover assembly	490
Right door assembly	491
Internal components (1 of 9)	492
Internal components (2 of 9)	494
Internal components (3 of 9)	496
Internal components (4 of 9)	498
Internal components (5 of 9)	500
Internal components (6 of 9)	502
Internal components (7 of 9)	504
Internal components (8 of 9)	506
Internal components (9 of 9)	508
Registration drive assembly	510
Process cartridge drive assembly (image drum drive)	511
Toner cartridge drive assembly (print cartridge drive)	512
Fuser drive assembly	514
Cassette assembly	516
Paper pickup assembly (1 of 3)	518
Paper pickup assembly (2 of 3)	520
Paper pickup assembly (3 of 3)	522
Manual feed pickup assembly (tray 1) (1 of 2)	524
Manual feed pickup assembly (tray 1) (2 of 2)	526
Registration assembly	528
Secondary transfer assembly (T2) (1 of 2)	530
Secondary transfer assembly (T2) (2 of 2)	532
Delivery feed assembly	533
Face down delivery assembly	534
Delivery cover assembly	535
Fuser assembly	536
PCB assemblies	537
Tray 4	538
Tray 4 main body	538
Tray 4 drive assembly	542
Tray 4 PCA location	543
Pedestal	544
Pedestal main body (1 of 2)	544
Pedestal main body (2 of 2)	545
Master parts lists	546
Alphabetical parts list	546
Numerical parts list	552

Match case Limit results 1 per page

ENWW

Chapter 5 Theory of operation

161

Dual-beam method

The laser/scanner unit contains two laser diodes in the laser unit. The printer employs the “dual-

beam method,” which scans two lines simultaneously.

Based on signals it receives from the DC controller and the formatter, the laser/scanner PCA in turn

signals the two laser diodes to emit laser beams. The beams strike a four-sided mirror that rotates at

a constant speed through the collimator lens and cylindrical lens. The beams reflect off of the mirror,

pass through a focusing lens and a reflective mirror, and focus on the photosensitive drum.

The scanning mirror, rotating at a constant speed, reflects the laser beams, which scan across the

drum at a constant speed. Then, a latent image is formed on the drum surface by constant-speed

rotation of the photosensitive drum and constant-speed scanning of the laser beams.

Figure 43.

Dual-beam method

First scan

Second scan

Third scan

Fourth scan

Feed direction

Image area

LD2 scan line

LD1 scan line