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HP Color LaserJet Enterprise CP4020 Service Manual - Page 48

Failure detection, TP2 or TP3: 100° C 212° F or lower

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◦ Current detection circuit ◦ Thermoswitch ● DC controller: The DC controller monitors the detected temperature of the main thermistor and sub thermistors. The DC controller deactivates the FIXING HEATER CONTROL signal and releases the relay to interrupt power supply to the fuser heater under the following conditions: ◦ TH1: 230° C (446° F) or higher ◦ TH2: 285° C (545° F) or higher ◦ TH3: 285° C (545° F) or higher ● Fuser-heater safety circuit: The fuser heater safety circuit monitors the detected temperature of the sub thermistors. The fuser heater safety circuit releases the relay to interrupt power supply to the fuser heater under the following conditions: ◦ TH2: 290° C (554° F) or higher ◦ TH3: 290° C (554° F) or higher ● Current-detection protection circuit: The current detection circuit monitors the current flowing through the fuser heater control circuit. The current detection circuit deactivates the fuser heater control circuit to interrupt power supply to the fuser heater when it detects the current higher than a specified value. ● Thermoswitch: If the temperature in the heaters is abnormally high, and the temperature in the thermoswitches exceeds a specified value, the contact to the thermoswitch breaks. Following are the thresholds for each thermoswitch: ◦ TP1: 270° C (518° F) or higher NOTE: When the thermoswitches reach this temperature, the temperature on the fuser rollers is about 320° C (608° F). Failure detection The DC controller determines a fuser unit failure, deactivates the FIXING HEATER CONTROL signal, releases the relay to interrupt power supply to the fuser heater, and notifies the formatter of a failure status when it encounters any of following conditions: ● Abnormally high temperatures: Temperatures are too high for any of the following components, at any time: ◦ TH1: 230° C (446° F) or higher ◦ TH2: 285° C (545° F) or higher ◦ TH3: 285° C (545° F) or higher ● Abnormally low temperatures: Temperatures are too low at any of the following components after the product has initialized. ◦ TH1: 120° C (248° F) or lower ◦ TP2 or TP3: 100° C (212° F) or lower ● Abnormal temperature rise: The DC controller determines an abnormal temperature rise if the detected temperature of TH1 does not rise 2° C within a specified time after the fuser motor is 16 Chapter 1 Theory of operation ENWW

Section	Page
Theory of operation	33
Basic operation	34
Sequence of operation	35
Engine-control system	36
DC controller	37
Solenoids	37
Clutches	38
Switches	38
Sensors	39
Motors	40
Fans	41
High-voltage power supply	42
Low-voltage power supply	44
Overcurrent/overvoltage protection	45
Safety	45
Voltage detection	45
Sleep (powersave) mode	45
Low-voltage power supply failure	45
Fuser control	46
Fuser temperature control	47
Fuser sleeve temperature protection	47
Failure detection	48
Fuser unit identification	49
Fuser unit life detection	49
Laser/scanner system	50
Laser/scanner failure	51
Protective-glass cleaners	51
Image-formation system	53
Image-formation process	55
Step 1: Pre-exposure	56
Step 2: Primary charging	56
Step 3: Laser-beam exposure	57
Step 4: Development	57
Step 5: Primary transfer	58
Step 6: Secondary transfer	58
Step 7: Separation	59
Step 8: Fusing	59
Step 9: ITB cleaning	60
Step 10: Drum cleaning	60
Print cartridge	60
Developing-roller engagement and disengagement	62
Intermediate transfer belt (ITB) unit	63
Primary-transfer-roller engagement and disengagement	64
ITB cleaning	66
Calibration	66
Color-misregistration control	67
Image-stabilization control	67
Pickup, feed, and delivery system	69
Pickup-and-feed unit	73
Cassette pickup	73
Cassette-presence detection	74
Cassette lift operation and cassette paper-presence detection	75
Cassette multiple-feed prevention	75
Multipurpose tray pickup	76
Paper feed	77
Skew-feed prevention	79
Paper detection	79
Feed speed control	80
Fusing and delivery unit	80
Loop control	81
Pressure-roller pressurization control	83
Duplexing unit (HP Color LaserJet CP4525dn, HP Color LaserJet CP4025dn, and HP Color LaserJet CP4525 ...	84
Duplexing reverse and feed control	84
Duplex print operation	85
Jam detection	87
Optional paper feeder	89
Motor control	91
Paper-feeder pickup and feed operation	92
Paper-size detection and cassette-presence detection	94
Paper-feeder cassette lift operation	95
Paper feeder jam detection	96
Removal and replacement	99
Introduction	100
Removal and replacement strategy	100
Electrostatic discharge	101
Required tools	101
Before performing service	102
After performing service	102
Post-service test	103
Print-quality test	103
Parts removal order	104
Customer self repair (CSR) components	106
Print cartridges	106
Toner-collection unit	108
Formatter PCA	110
Hard drive	111
Remove the hard drive	111
Memory DIMM	113
Remove the memory DIMM	113
Enable memory	114
Tray	116
Fuser	117
Feed and separation rollers (Trays 2-5)	118
Pickup roller (Tray 1)	119
Secondary transfer roller	122
Reinstall the transfer roller	123
Intermediate transfer belt (ITB)	124
External panels, covers, and doors	127
Identification and location	127
Upper-left cover	128
Power-supply cover	130
Left cover	131
Remove the left cover	131
Front-top cover	132
Remove the front-top cover	132
Rear-top cover	134
Remove the rear-top cover	134
Right-front cover	135
Remove the right-front cover	135
Reinstall the power button	136
Control-panel assembly	137
Remove the control-panel assembly	137
Front-door assembly	139
Remove the front-door assembly	139
Right-rear cover	142
Remove the right-rear cover	142
Rear cover	144
Remove the rear cover	144
Right-door assembly	145
Internal assemblies	150
Cassette feed guide	150
Secondary transfer assembly	151
Reinstall the secondary transfer assembly	152
Separation pad (Tray 1)	153
Remove the separation pad (Tray 1)	153
Registration density (RD) sensor assembly	156
Remove the RD sensor assembly	156
Registration assembly	160
Remove the registration assembly	161
Residual-toner-feed motor	165
Remove the residual-toner-feed motor	165
Residual-toner duct and feed assembly	166
Remove the residual-toner duct and feed assembly	166
Cartridge fan and environmental sensor	169
Remove the cartridge fan and environmental sensor	169
Toner-collection sensor and scanner-thermistor assembly	173
Remove the toner-collection sensor and scanner-thermistor assembly	173
Delivery fan	175
Remove the delivery fan	175
Delivery assembly	177
Remove the delivery assembly	177
Reinstall the delivery assembly	181
Duplex-drive assembly	183
Remove the duplex-drive assembly	183
Power-supply fan	184
Remove the power-supply fan	184
Interconnect board (ICB)	185
Remove the ICB	185
DC controller PCA only	187
Remove the DC controller PCA only	187
Low-voltage power supply (LVPS)	189
Remove the low-voltage power supply	189
DC controller PCA and tray	193
Remove the DC controller PCA and tray	193
High-voltage power supply lower (HVPS-D)	195
Remove the high-voltage power supply lower	195
Reinstall the high-voltage power supply lower	199
Developing-disengagement motor	200
Remove the developing-disengagement motor	200
Exhaust fan and fan duct	201
Remove the exhaust fan and fan duct	201
Reinstall the exhaust fan and fan duct	203
Pickup motor	204
Remove the pickup motor	204
Lifter-drive assembly	205
Remove the lifter-drive assembly	205
Lifter base assembly	207
Remove the lifter base assembly	207
Reinstall the lifter base assembly	208
Tray-pickup drive assembly	210
Remove the tray-pickup drive assembly	210
Tray-pickup assembly	212
Remove the tray-pickup assembly	212
Laser/scanner assembly (Y/M)	218
Remove the laser/scanner assembly (Y/M)	219
Laser/scanner assembly (C/Bk)	222
Remove the laser/scanner assembly (C/Bk)	223
Reinstall the protective glass cleaner (PGC) actuators	225
High-voltage power supply upper (HVPS-T)	228
Remove the high-voltage power supply upper	228
Reinstall the high-voltage power supply upper	230
Yellow, magenta, cyan, and black drum motors	231
Remove the yellow, magenta, cyan, and black drum motors	231
Fuser motor	232
Remove the fuser motor	233
ITB motor	234
Remove the ITB motor	234
Main-drive assembly	235
Remove the main-drive assembly	236
Reinstall the main-drive assembly	239
Fuser-drive assembly	243
Remove the fuser-drive assembly	244
Reinstall the fuser-drive assembly	247
Optional paper feeder assemblies (1 x 500-sheet and 3 x 500-sheet)	248
Front door (optional paper feeder)	248
Rear cover (optional paper feeder)	250
Right-front cover (optional paper feeder)	251
Right door (optional paper feeder)	252
Left cover (optional paper feeder)	254
Remove the left cover (optional paper feeder)	254
Right cover (optional paper feeder)	256
Remove the right cover (optional paper feeder)	256
Rear-right cover (optional paper feeder)	257
Remove the rear-right cover (optional paper feeder)	257
Pickup assembly (optional paper feeder)	258
Remove the pickup assembly (optional paper feeder)	258
Lifter assembly (optional paper feeder)	261
Remove the lifter assembly (optional paper feeder)	261
Lifter-drive assembly (optional paper feeder)	262
Remove the lifter-drive assembly (optional paper feeder)	262
Pickup motor assembly (optional paper feeder)	263
Remove the pickup motor (optional paper feeder) assembly	263
Controller PCA (optional paper feeder)	264
Remove the controller PCA (optional paper feeder)	264
Solve problems	265
Solve problems checklist	266
Menu map	268
Troubleshooting process	269
Determine the problem source	269
Pre-troubleshooting checklist	269
Troubleshooting flowchart	271
Power subsystem	272
Power-on checks	272
Power-on troubleshooting overview	272
Tools for troubleshooting	274
Individual component diagnostics	274
LED diagnostics	274
Understand lights on the formatter	274
HP Jetdirect LEDs	274
Heartbeat LED	275
Engine diagnostics	275
Defeating interlocks	275
Disable cartridge check	276
Engine-test button	276
Paper-path test	277
Manual sensor test (special-mode test)	278
A TOP (top of page) sensor	279
B and C loop sensors	280
D fuser delivery sensor	281
E duplex re-pickup sensor	282
F output bin full sensor	283
I developer alienation	284
J fuser pressure-release sensor	285
K primary transfer-roller-disengagement sensor	286
L media sensor	288
M front-door switch	289
N right-door switch	290
Manual sensor test 2 (special-mode test)	291
O Tray 1 paper present sensor	293
P Tray 2 paper present sensor	294
Q Tray 2 paper surface 1 and 2 sensors	295
R Tray 2 paper size switches	296
S Tray 3 paper present sensor	297
T Tray 3 feed sensor	297
U Tray 3 paper surface 1 and 2 sensors	297
V Tray 3 paper size switches	297
W Tray 4 paper present sensor	297
X Tray 4 feed sensor	297
Y Tray 4 paper surface 1 and 2 sensors	297
Z Tray 4 paper size switches	298
a Tray 5 paper present sensor	298
b Tray 5 feed sensor	298
c Tray 5 paper surface 1 and 2 sensors	298
d Tray 5 paper size switches	298
5V laser and 24V interlock and logic switches (and power switch)	299
Location and testing	299
Defeating	300
New ITB sensor	303
Tray 3, 4, and 5 right door switch	304
Paper-path sensors test	305
Print/stop test	305
Component tests	306
Component test (special-mode test)	306
Diagrams	309
Block diagrams	309
Plug/jack locations	312
Location of connectors	313
DC controller connector locations	313
Controller PCA (1 x 500-sheet and 3 x 500-sheet optional paper feeders)	315
Locations of major components	316
General timing chart	326
Circuit diagrams	327
HP Easy Printer Care	331
Open the HP Easy Printer Care software	331
HP Easy Printer Care software sections	331
Internal print-quality test pages	334
Print-quality-troubleshooting pages	334
Diagnostics page	337
Cleaning page	338
Configuration page	339
Configuration page	339
HP embedded Jetdirect page	341
Embedded protocol page	342
Finding important information on the configuration pages	343
Color-band test	343
Print-quality troubleshooting tools	344
Repetitive defects ruler	344
Calibrate the product	345
Control panel menus	346
Control panel menus	346
Show Me How menu	346
Retrieve job menu	346
Information menu	349
Paper handling menu	349
Manage supplies menu	350
Configure device menu	353
Printing menu	353
PCL sub-menu	355
Print Quality menu	356
System setup menu	361
I/O menu	366
Resets menu	374
Diagnostics menu	374
Service menu	376
Interpret control-panel messages	377
Control-panel message types	377
Control-panel messages	377
Event log messages	408
Print an event log	408
Show an event log	408
Sample event log	409
Clear the event log	409
Event log message table	410
Clear paper jams	415
Common causes of jams	415
Jam locations	418
Clear jams in the right door	419
Clear jams in the output bin area	422
Clear jams in Tray 1	422
Clear jams in Tray 2 or optional Trays 3, 4, or 5	424
Clear jams in the lower right door (Tray 3, 4, or 5)	425
Jam causes and solutions	426
Jams in the output bin	426
Jams in the fuser and transfer area	426
Jams in the duplex area (HP Color LaserJet CP4525dn, HP Color LaserJet CP4025dn, and HP Color LaserJ ...	429
Jams in Tray 1, Tray 2 and internal paper path	431
Jams in Tray 3, 4, and 5	432
Change jam recovery	434
Solve paper-handling problems	435
Product feeds multiple sheets	435
Product feeds incorrect page size	435
Product pulls from incorrect tray	435
Paper does not feed automatically	436
Paper does not feed from Tray 2, 3, 4, or 5	436
Transparencies or glossy paper will not feed	437
Envelopes jam or will not feed in the product	437
Output is curled or wrinkled	438
Product will not duplex or duplexes incorrectly	438
Use manual print modes	440
Solve image-quality problems	442
Image defects table	442
Clean the product	448
Clean the paper path	448
Solve performance problems	449
Solve connectivity problems	450
Solve direct-connect problems	450
Solve network problems	450
Service mode functions	452
Service menu	452
Product resets	455
Restore factory-set defaults	455
Hard disk initialization (optional)	455
NVRAM initialization	455
Product cold reset	456
Product updates	456
Parts and diagrams	457
Order parts, accessories, and supplies	458
Part numbers	459
Accessories	459
Print cartridges and toner collection unit	459
Memory	459
Cables and interfaces	459
Customer self repair (CSR) parts	460
Service maintenance kits	460
Unique components	461
Screws	462
How to use the parts lists and diagrams	463
External covers, panels, and doors	464
Right door assembly	466
Front door assembly	468
Internal components	470
Internal components (1 of 7)	470
Internal components (2 of 7)	472
Internal components (3 of 7)	474
Internal components (4 of 7)	476
Internal components (5 of 7)	478
Internal components (6 of 7)	480
Internal components (7 of 7)	482
Cassettes 2-5	484
Paper pickup assembly	486
Tray 1 paper pickup assembly	488
Registration assembly	490
Secondary transfer assembly	492
Delivery assembly	494
Fuser assembly	496
PCAs	498
Assessories	500
Paper feeders	500
Paper feeder external covers, panels, and doors	502
1 X 500 paper feeder main body	504
3 X 500 paper feeder main body	506
Alphabetical parts list	508
Numerical parts list	516
Service and support	525
Hewlett-Packard limited warranty statement	526
HP's Premium Protection Warranty: LaserJet print cartridge limited warranty statement	527
HP Color LaserJet Fuser Kit Limited Warranty Statement	528
End User License Agreement	529
Customer self-repair warranty service	531
Customer support	532
Product specifications	533
Physical specifications	534
Performance specifications	534
Electrical specifications	534
Acoustic specifications	535
Environmental specifications	535
Skew specifications	536
Regulatory information	537
FCC regulations	538
Environmental product stewardship program	539
Protecting the environment	539
Ozone production	539
Power consumption	539
Toner consumption	539
Paper use	539
Plastics	539
HP LaserJet print supplies	539
Return and recycling instructions	540
United States and Puerto Rico	540
Multiple returns (more than one cartridge)	540
Single returns	540
Shipping	540
Residents of Alaska and Hawaii	540
Non-U.S. returns	540
Paper	540
Material restrictions	541
Disposal of waste equipment by users in private households in the European Union	541
Chemical substances	541
Material Safety Data Sheet (MSDS)	542
For more information	542
Declaration of Conformity	543
Safety statements	544
Laser safety	544
Canadian DOC regulations	544
VCCI statement (Japan)	544
Power cord instructions	544
Power cord statement (Japan)	544
EMC statement (China)	545
EMC statement (Korea)	545
EMI statement (Taiwan)	545
Laser statement for Finland	545
GS statement (Germany)	546
Substances Table (China)	546
Restriction on Hazardous Substances statement (Turkey)	546

Match case Limit results 1 per page

◦

Current detection circuit

◦

Thermoswitch

●

DC controller

: The DC controller monitors the detected temperature of the main thermistor and

sub thermistors. The DC controller deactivates the FIXING HEATER CONTROL signal and

releases the relay to interrupt power supply to the fuser heater under the following conditions:

◦

TH1: 230° C (446° F) or higher

◦

TH2: 285° C (545° F) or higher

◦

TH3: 285° C (545° F) or higher

●

Fuser-heater safety circuit

: The fuser heater safety circuit monitors the detected temperature of

the sub thermistors. The fuser heater safety circuit releases the relay to interrupt power supply to

the fuser heater under the following conditions:

◦

TH2: 290° C (554° F) or higher

◦

TH3: 290° C (554° F) or higher

●

Current-detection protection circuit

: The current detection circuit monitors the current flowing

through the fuser heater control circuit. The current detection circuit deactivates the fuser heater

control circuit to interrupt power supply to the fuser heater when it detects the current higher than

a specified value.

●

Thermoswitch

: If the temperature in the heaters is abnormally high, and the temperature in the

thermoswitches exceeds a specified value, the contact to the thermoswitch breaks. Following are

the thresholds for each thermoswitch:

◦

TP1: 270° C (518° F) or higher

NOTE:

When the thermoswitches reach this temperature, the temperature on the fuser rollers is about

320° C (608° F).

Failure detection

The DC controller determines a fuser unit failure, deactivates the FIXING HEATER CONTROL signal,

releases the relay to interrupt power supply to the fuser heater, and notifies the formatter of a failure

status when it encounters any of following conditions:

●

Abnormally high temperatures

: Temperatures are too high for any of the following components,

at any time:

◦

TH1: 230° C (446° F) or higher

◦

TH2: 285° C (545° F) or higher

◦

TH3: 285° C (545° F) or higher

●

Abnormally low temperatures

: Temperatures are too low at any of the following components

after the product has initialized.

◦

TH1: 120° C (248° F) or lower

◦

TP2 or TP3: 100° C (212° F) or lower

●

Abnormal temperature rise

: The DC controller determines an abnormal temperature rise if the

detected temperature of TH1 does not rise 2° C within a specified time after the fuser motor is

Chapter 1

Theory of operation

ENWW