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HP 8550 Service Manual - Page 729

N, O, MS1 ADF switch 279

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MISC-P (printer unit) 95 MISC-R (reader unit) 95 misfeeds improper gap adjustment 159 MJ (text detection) signal chromatic identification 214 theory of operation 211 model numbers 35 modes adjust 83 AE 84, 204 anti-see-through 213 background omission 213 counter 111 display 65 double-sided original 252 feeder 114 full color 50 I/O 77 ID 50 ITD cleaning rotation 99, 100 low power 235 mono-color 50 photo 109 reduced page composition 255, 263 run/check 93 separation belt cleaning 115 service 60 standard 54 standard, returning to 139 test print 108 text 109 text/photo/map 89 user 49 modified top cover assembly, part numbers 119 motor driver, copy module diagrams 589 part numbers 589 motors automatic document feeder (ADF) 249, 286 automatic document feeder (ADF), removing 387, 452 belt 249 belt drive assembly 634, 635 belt, adjusting tension 391 belt, control 277 belt, removing 389 delivery 249, 267 delivery, removing 394 drive pulses, scanner motor 192 driver diagrams 589 driver part numbers 589 feed, troubleshooting 542 feeder 249 feeder, removing 387, 452 high-capacity input (HCI) 316 laser scanner, theory of operation 187 lifter 310 lifter, removing 452 paper feed, diagrams and part numbers 632 part numbers 693 pick-up 249, 256, 275 pick-up, high-capacity input (HCI) 307 pick-up, removing 385, 452, 453 scanner 191 scanner, removing 338 scanner, troubleshooting 525 sensors 81 mounting original-width-detection volume 383 ROM DIMMs 342 mounting hardware automatic document feeder (ADF) 606 high-capacity input (HCI) 653 part numbers 693 MOVE signal 192 moving the copier powering off 177 procedures for user 177 MS1 (ADF switch) 279 MS1 (open/closed switch) adjustments 151 MSDS (Material Safety Data Sheet) 43 multifeeder jams in 73 troubleshooting 544 N navigating service mode screens 63 networks, troubleshooting 457 noise copy module 25 noise filter diagrams 583 part numbers 583 non-HP components 457 non-image width, adjusting 122 numbers model 35 originals copied 284 phone 40 serial 35 numerical list, part numbers 672 nuts, part numbers 694 O odd/even bit synthesis 203 offset level, RGB 68 online support 40 opacity, guidelines for 29 EN Index 727

Section	Page
Contents	5
Figures	7
Tables	19
Product information	23
Introduction	25
Copy module	25
Features	25
Specifications	26
Overview	28
Automatic document feeder (ADF)	30
Features	30
Specifications	31
Overview	32
Side high-capacity input (side HCI)	34
Features	34
Specifications	34
Overview	35
Model and serial numbers	37
Safety and regulatory information	37
Declaration of conformity	37
FCC regulations	38
Service approach	39
Service approach overview	41
Parts and supplies	41
Ordering	42
Obtaining related documentation and software	42
Ordering consumables	43
Ordering FRUs	43
Parts exchange program	43
Technical assistance	44
List Server	44
HP ASAP	44
HP FIRST	45
Dealer Response Line	46
HP Software Distribution Center	46
HP Direct	46
Customer Support Sales Center	46
Parts identification	46
Customer Information Centers	46
HP Customer Care Centers (CCC)	47
Warranty	48
Operational overview	49
Control panel	51
Copy module functionality	53
User mode	54
Automatic gradation adjustment	59
Cold reset	59
Original-set indicator (ADF)	60
Warnings and actions	60
Self-diagnostic messages	61
Service mode	62
Overview	62
Navigating service mode screens	65
Copier, display mode (DISPLAY)	67
Copier, I/O mode (I/O)	79
Copier, adjust mode (ADJUST)	85
Copier, run/check mode (FUNCTION)	95
Copier, machine settings (OPTION) mode	100
Copier, test print mode (TEST)	110
Copier, counter mode	113
Feeder	116
Adjustments and maintenance	119
Overview	121
MFP print engine adjustments	121
Parts unique to the HP LaserJet 8550MFP print engine	121
Adjustments unique to the HP LaserJet 8550MFP print engine	122
Copy module adjustments	123
End-user adjustments	123
Mechanical and electrical adjustments	124
Required adjustments when replacing parts or upgrading	131
Upgrading and localizing the copy module firmware	137
ADF adjustments	142
Mechanical adjustments	143
Electrical adjustments	157
Replacing the DADF controller PCB	160
Side HCI adjustments	161
Gap between the printer and the side HCI	161
Base plate position	162
Paper-size change (A4 or letter)	163
Periodically replaced parts	165
Cleaning	166
Cleaning by an end-user	166
Cleaning by service technicians	166
Solvents	166
Cleaning parts on the copy module	167
Cleaning ADF parts	169
Cleaning side HCI parts	175
Lubricating	176
Theory of operation	177
Introduction	179
Notes on the power switch	179
Copy module	180
Functional construction	180
Outline of electrical circuitry	181
Inputs to and outputs from the major PCBs	182
Basic sequence of operations	185
Sequence of operations during copying	187
Copy module exposure system	190
Scanner home position sensor and operation	192
Scanner motor	193
Controlling the scanning lamp	195
Identifying the size of originals when copying from the glass	199
Copy module image processing system	202
CCD	203
CCD driver	204
AP-IP (analog image processing) PCB	205
Digital image processing	208
Control panel	234
Fan	236
Power supply	237
ADF	246
ADF electrical circuitry	246
Communication with the copy module	247
Inputs and outputs to the DADF controller PCB	248
Basic operation	251
Functional overview	252
Picking up originals	258
Reversal operation	263
Reduced page composition	265
Delivery operation	268
Detecting originals	271
Controlling the pick-up motor	277
Controlling the belt motor	279
Detecting jams	281
Improper placement of originals	284
Power supply	287
Motors, solenoids, and sensors	288
PCBs	289
Indicator PCB	290
General timing charts	290
Side HCI	306
Pick-up feed system	309
Power supply	316
Sensors	317
Solenoids and motors	318
PCBs	319
List of variable resistors (VR), LEDs, check pins by PCB	320
Input and output signals to the deck controller PCB	323
General circuit diagram	326
Removal and replacement	329
Required tools	333
Repair notices	334
Copy module	335
Identifying the external covers	335
Removing the lower front cover	336
Removing the upper right cover	336
Removing the upper rear cover	337
Removing the upper left cover	337
Removing the rear cover	338
Removing the upper front cover	339
Removing the scanner motor	340
Removing the scanner motor driver PCB	341
Removing DIMMs on the reader controller PCB	342
Removing the control panel	346
Removing the LCD assembly	348
Removing the flexible cable	355
Removing the scanning lamp and scanning lamp heater	359
Removing the standard white plate cover	365
Removing the intensity-detection PCB	366
Removing the lens-mount cover and CCD unit	367
Removing the electrical unit pullout	369
Removing the reader controller PCB	372
Removing the ECO-2 PCB	373
Removing the AP-IP PCB	374
Removing the copy module main power supply PCB (DCP1)	375
Removing the accessories power supply PCB (DCP2)	376
Removing the power supply cooling fan (FM4)	377
Removing the inverter PCB unit	378
Automatic document feeder (ADF)	379
Identifying external covers	379
Removing the ADF	380
Removing the body cover	382
Mounting the original-width detecting volume	385
Removing the pick-up motor unit	387
Removing the ADF motor unit	389
Removing the belt motor	391
Removing the clutch unit	394
Removing the delivery motor	396
Removing the pick-up roller	398
Removing the separation belt unit	400
Removing the feeding roller unit	401
Removing the registration roller	404
Removing the delivery/reversing roller	409
Removing the delivery roller unit (bottom pick-up mode)	416
Removing the delivery roller unit (top pick-up mode)	418
Removing the reversing guide	421
Removing the stopper plate solenoid	424
Positioning the paper-retaining plate solenoid (SL2)	426
Positioning the paper-deflecting solenoid (SL3)	428
Removing the stamp solenoid	429
Removing the feeding belt	433
Side HCI	436
Identifying the external covers	436
Removing the upper left cover	437
Removing the front cover	437
Removing the rear cover	438
Removing the upper right cover	438
Removing the pick-up unit	439
Removing the pick-up roller	442
Removing the feed roller and separation roller	443
Removing the lifter wire	444
Removing the lifter motor (M1)	454
Removing the feeder motor (M2)	454
Removing the pick-up motor (M3)	455
Removing the deck controller PCB	455
Removing the power supply PCB	456
Troubleshooting	457
System-to-device troubleshooting	459
Pre-troubleshooting checklist	459
Process of elimination	460
Copy module troubleshooting	462
Overview	462
Necessary adjustments for replaced parts	462
Image fault troubleshooting	464
Image faults	478
Numbered error codes	495
Faults not identified by error codes	521
Using the copy module service mode to test parts	528
ADF troubleshooting	530
Fault isolation	530
Numbered error codes	531
Self-diagnosis	535
Check the output of the DADF controller PCB	536
Side HCI troubleshooting	537
Overview	537
User and service LEDs	538
Sensor and switch tests	540
Test pick-up	541
Faults not identified by error codes	543
Parts and diagrams	549
How to use this chapter	553
Printer parts unique to the HPColor LaserJet 8550MFP	554
Stand	557
Screw/ring kit	557
Stand assembly	558
Copy module	560
Screw/ring kit	560
Belt kit	561
Gear/pulley kit	562
Spring kit	562
Assembly location diagram	563
External covers and panels	564
Internal components	566
Power cord terminal assembly	572
Control panel assembly	574
Copyboard cover assembly	576
Mirror assembly 1	578
Electrical tray assembly	580
Dc power supply PCA	582
APC power supply PCA	584
Noise filter PCA	585
Control panel PCA	586
Control panel CPU PCA	587
Control panel inverter PCA	588
Reader controller PCA	589
Analog image processor PCA	590
Motor driver PCA	591
Inverter PCA	592
Connectors	593
ADF	602
Belt kit	602
Bushing kit	603
Gear/pulley kit	603
Pin kit	604
Screw/ring kit	604
Spring kit	606
Assembly locations	607
Mounting hardware	608
External covers and panels	609
DF assembly	610
Document tray assembly	614
Upper cover assembly	616
RF assembly	618
Right paper delivery assembly	632
Paper feed motor assembly	634
Belt drive motor assembly	636
Upper paper guide assembly	638
Lower paper guide assembly	640
Separation roller assembly	642
Paper separation assembly	644
RDF controller PCA	646
Connectors	647
Side HCI	651
Bushing kit	651
Gear/pulley kit	651
Screw/ring kit	652
Spring kit	653
Assembly locations	654
Mounting hardware	655
External covers and panels	656
Internal components	658
Lifter drive assembly	665
Paper pick-up assembly	666
Deck controller PCA	670
Connectors	671
Numerical parts list	674
Alphabetical parts list	682
Index	713
A	713
B	715
C	716
D	720
E	722
F	722
G	724
H	724
I	725
J	726
K	726
L	726
M	728
N	729
O	729
P	730
Q	733
R	733
S	735
T	739
U	740
V	740
W	740
X	741
Y	741

Match case Limit results 1 per page

Index

727

MISC-P (printer unit) 95

MISC-R (reader unit) 95

misfeeds

improper gap adjustment 159

MJ (text detection) signal

chromatic identification 214

theory of operation 211

model numbers 35

modes

adjust 83

AE 84, 204

anti-see-through 213

background omission 213

counter 111

display 65

double-sided original 252

feeder 114

full color 50

I/O 77

ID 50

ITD cleaning rotation 99, 100

low power 235

mono-color 50

photo 109

reduced page composition 255, 263

run/check 93

separation belt cleaning 115

service 60

standard 54

standard, returning to 139

test print 108

text 109

text/photo/map 89

user 49

modified top cover assembly, part numbers 119

motor driver, copy module

diagrams 589

part numbers 589

motors

automatic document feeder (ADF) 249, 286

automatic document feeder (ADF), removing 387,

452

belt 249

belt drive assembly 634, 635

belt, adjusting tension 391

belt, control 277

belt, removing 389

delivery 249, 267

delivery, removing 394

drive pulses, scanner motor 192

driver diagrams 589

driver part numbers 589

feed, troubleshooting 542

feeder 249

feeder, removing 387, 452

high-capacity input (HCI) 316

laser scanner, theory of operation 187

lifter 310

lifter, removing 452

paper feed, diagrams and part numbers 632

part numbers 693

pick-up 249, 256, 275

pick-up, high-capacity input (HCI) 307

pick-up, removing 385, 452, 453

scanner 191

scanner, removing 338

scanner, troubleshooting 525

sensors 81

mounting

original-width-detection volume 383

ROM DIMMs 342

mounting hardware

automatic document feeder (ADF) 606

high-capacity input (HCI) 653

part numbers 693

MOVE signal 192

moving the copier

powering off 177

procedures for user 177

MS1 (ADF switch) 279

MS1 (open/closed switch)

adjustments 151

MSDS (Material Safety Data Sheet) 43

multifeeder

jams in 73

troubleshooting 544

navigating service mode screens 63

networks, troubleshooting 457

noise

copy module 25

noise filter

diagrams 583

part numbers 583

non-HP components 457

non-image width, adjusting 122

numbers

model 35

originals copied 284

phone 40

serial 35

numerical list, part numbers 672

nuts, part numbers 694

odd/even bit synthesis 203

offset level, RGB 68

online support 40

opacity, guidelines for 29