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HP LaserJet Pro P1102 HP LaserJet Professional P1100 Series Printer - Service - Page 35

Overcurrent/overvoltage protection

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Overcurrent/overvoltage protection The low-voltage power supply has a protective function against overcurrent and overvoltage to prevent failures in the power supply circuit. If an overcurrent or overvoltage condition occurs, the system automatically cuts off the output voltage. If the dc power is not being supplied from the low-voltage power supply, the protective function might be running. In such case, turn off the power switch and unplug the power cord. Do not plug in the power cord or turn on the power switch again until the cause is found. WARNING! If you believe the overcurrent or overvoltage protection circuits have been activated, do not plug in the product power cord or turn on the product power until the cause of the failure is found and corrected. In addition, two fuses in the low-voltage power supply protect against overcurrent. If overcurrent flows into the ac line, the fuses melt and cut off the power distribution. ENWW Engine-control system 17

Section	Page
Theory of operation	19
Basic operation	20
Major product systems	20
Product block diagram	20
Sequence of operation	21
Normal sequence of operation	21
Formatter-control system	22
Sleep mode	22
Input/output	22
CPU	22
Memory	22
Firmware	23
Memory use	23
PJL overview	23
LEDM overview	23
ACL overview	23
Control panel	24
Wireless PCA	24
Engine-control system	25
Motors, fans, clutches, solenoids, switches, and sensors	26
DC controller operations	29
Fuser-control circuit	30
Fuser failure detection	31
Fuser temperature control	32
Fuser protective function	33
Pressure roller cleaning	33
Low-voltage power supply	34
Overcurrent/overvoltage protection	35
High-voltage power supply	36
Laser/scanner system	37
Laser failure detection	38
Image-formation system	39
Electrophotographic process	39
Image formation process	41
Latent-image formation stage	42
Primary charging	42
Laser beam exposure	42
Developing stage	43
Print cartridge	43
Transfer stage	44
Fusing stage	45
Cleaning stage	45
Pickup, feed, and delivery system	46
Photo sensors and switches	47
Input tray, main-input tray, or priority input slot	48
Jam detection	48
Removal and replacement	49
Introduction	50
Removal and replacement strategy	50
Electrostatic discharge	51
Required tools	51
Before performing service	52
After performing service	52
Post-service test	53
Print-quality test	53
Parts removal order	54
Pickup roller	55
Separation pad	56
Transfer roller	57
Covers	58
Input tray or main-input tray	58
Output bin tray extension	59
Front cover	60
Remove the front cover	60
Left cover	61
Remove the left cover	61
Right cover	64
Remove the right cover	64
Cartridge door	66
Remove the cartridge door	66
Face-down cover	68
Remove the face-down cover	68
Rear cover	70
Remove the rear cover	70
Main assemblies	72
Formatter PCA	72
Remove the formatter PCA	73
Wireless PCA	75
Remove the wireless PCA	75
Laser/scanner assembly	76
Remove the laser/scanner assembly	76
Reinstall the laser/scanner assembly	78
Pickup assembly	79
Remove the pickup assembly	79
Reinstall the pickup assembly	83
Fuser	85
Remove the fuser	85
Reinstall the fuser	89
Main motor	90
Remove the main motor	90
Reinstall the main-motor drive belt	94
Pickup solenoid	95
Remove the pickup solenoid	95
Engine controller PCA	98
Remove the engine controller PCA	98
Reinstall the engine controller PCA	102
Solve problems	105
Solve problems checklist	106
Troubleshooting process	109
Determine the problem source	109
Power subsystem	110
Power-on checks	110
Tools for troubleshooting	111
Individual component diagnostics	111
Engine diagnostics	111
Engine-test button	111
Components tests	112
Drum rotation functional check	112
Half self-test functional check	112
Diagrams	113
Plug/jack locations	113
Location of connectors	114
Locations of major components	115
General timing charts	117
General circuit diagram	118
Internal print-quality test pages	120
Cleaning page	120
Configuration page	120
Print-quality troubleshooting tools	121
Repetitive defect ruler	121
Interpret control-panel light patterns	121
Clear jams	125
Common causes of jams	125
Jam locations	126
Clear jams from the input tray	127
Clear jams from the output areas	129
Clear jams from inside the product	131
Solve repeated jams	132
Change jam recovery	132
Solve paper-handling problems	134
Solve image-quality problems	135
Image defect table	135
Light print or faded	135
Toner specks	135
Dropouts	136
Vertical lines	136
Gray background	136
Toner smear	136
Loose toner	137
Vertical repetitive defects	137
Misformed characters	137
Page skew	137
Curl or wave	138
Wrinkles or creases	138
Toner scatter outline	138
Moisture	139
Optimize and improve image quality	140
Change print density	140
Clean the product	141
Clean the pickup roller	141
Clean the paper path	142
Clean the print-cartridge area	144
Clean the exterior	146
Solve performance problems	147
Solve connectivity problems	148
Solve direct-connect problems	148
Solve wireless problems	148
Service mode functions	150
Product resets	150
Product updates	151
Parts and diagrams	153
Order parts by authorized service providers	154
Order parts, accessories, and supplies	154
Related documentation and software	154
Supplies part numbers	154
Customer self repair parts	155
Service parts	155
Whole-unit replacement part numbers	155
How to use the parts lists and diagrams	156
Assembly locations	157
Base product	157
Covers	158
Base model	158
Wireless model	160
Internal assemblies	162
Internal assemblies (1 of 3)	162
Internal assemblies (2 of 3)	164
Internal assemblies (3 of 3)	166
PCAs	168
Alphabetical parts list	170
Numerical parts list	173
Service and support	177
Hewlett-Packard limited warranty statement	178
HP's Premium Protection Warranty: LaserJet print cartridge limited warranty statement	179
End User License Agreement	180
Customer self-repair warranty service	182
Customer support	182
Repack the product	183
Service information form	184
Specifications	185
Physical specifications	186
Power consumption	186
Acoustic specifications	186
Environmental specifications	187
Regulatory information	189
FCC regulations	190
Declaration of conformity (base models)	191
Declaration of conformity (wireless models)	192
Certificate of Volatility	193
Safety statements	195
Laser safety	195
Canadian DOC regulations	195
VCCI statement (Japan)	195
Power cord instructions	195
Power cord statement (Japan)	195
EMC statement (Korea)	195
Laser statement for Finland	196
GS statement (Germany)	196
Substances Table (China)	197
Additional statements for wireless products	198
FCC compliance statement—United States	198
Australia statement	198
Brazil ANATEL statement	198
Canadian statements	198
European Union regulatory notice	198
Notice for use in France	199
Notice for use in Russia	199
Korean statement	199
Taiwan statement	199

Match case Limit results 1 per page

Overcurrent/overvoltage protection

The low-voltage power supply has a protective function against overcurrent and overvoltage to prevent

failures in the power supply circuit. If an overcurrent or overvoltage condition occurs, the system

automatically cuts off the output voltage.

If the dc power is not being supplied from the low-voltage power supply, the protective function might

be running. In such case, turn off the power switch and unplug the power cord. Do not plug in the power

cord or turn on the power switch again until the cause is found.

WARNING!

If you believe the overcurrent or overvoltage protection circuits have been activated, do

not plug in the product power cord or turn on the product power until the cause of the failure is found

and corrected.

In addition, two fuses in the low-voltage power supply protect against overcurrent. If overcurrent flows

into the ac line, the fuses melt and cut off the power distribution.

ENWW

Engine-control system