HP Laserjet 5 Service Manual

							Printed on
Recycled Paper
*C3990-90991*
*C3990-90991*
C3990-90991
HP LaserJet 5L and 6L Printer
Service Manual
Copyright© 1997
Hewlett Packard Co.
Printed in USA 9/97Manual Part No.
C3990-90991
HP LaserJet 5L and 6L Printer (C3941/C3990) Service Manual 
						

							Service Manual
HP LaserJet 5L HP LaserJet 6L
(C3941A) (C3990A) 
						

							© Copyright Hewlett-Packard
Company 1997
All Rights Reserved.
Reproduction, adaptation, or
translation without prior
written permission is
prohibited, except as allowed
under the copyright laws.
Publication number
C3990-90991
First edition, May 1997Warranty
The information contained in
this document is subject to
change without notice.
Hewlett-Packard makes no
warranty of any kind with
regard to this material,
including, but not limited to,
the implied warranties or
merchantability and fitness for
a particular purpose.
Hewlett-Packard shall not be
liable for errors contained
herein or for incidental or
consequential damaged in
connection with the furnishing,
performance, or use of this
material.WARNING
Electrical Shock Hazard
To avoid electrical shock, use
only supplied power cords and
connect only to properly
grounded (3-hole) wall outlets.
Hewlett-Packard Company
11311 Chinden Boulevard
Boise, Idaho 83714 
						

							Conventions
This manual uses the following conventions:
Coloris used to emphasize items which are important to the material under
discussion.
The names of major printer parts and assemblies are CAPITALIZED.
Boldis used for emphasis, particularly in situations whereitalictype would be
confusing.
Italic typeis used to indicate related documents or emphasis.
NoteNotes contain important information set off from the text.
CautionCaution messages alert you to the possibility of damage to equipment or loss of data.
WARNING!Warning messages alert you to the possibility of personal injury.
iii 
						

							Chapter Descriptions
1Product Information
Orientation to the printer, as well as the service and repair philosophy, is discussed.
Information on obtaining assistance and warranty is also here.
2Site Requirements
Here are recommendations pertaining to installation requirements.
3Operating Overview
This chapter has detailed information about the Control Panel. Sample self tests and
printer reset information are also included.
4Maintenance
Turn to this chapter for information about printer cleaning and care.
5Functional Overview
Here you will find the basic theory-of-operation information required to understand
the various printer systems and how they function together.
6Removal and Replacement
This chapter contains the step-by-step procedures for replacing printer field
replaceable units (FRUs). Assemblies are grouped by location in the printer.
7Troubleshooting
Diagnose printer problems here. A preliminary troubleshooting table is followed by
error messages, image defect samples, and diagnostic tools.
8Parts and Diagrams
Look here to find any field replaceable unit (FRU) in the printer.  Exploded view
drawings are accompanied by complete part number tables.
AParts Index
All parts are sorted and cross-referenced here by part number and name.
BRegulatory Information
Here are required statements regarding RFI and laser safety.
CService Notes
Service Notes for HP LaserJet 5L concerning paper jams appear here.
Subject Index
Use the subject index to quickly locate any information in the manual.
iv 
						

							List of Figures
Figure 1-1 HP LaserJet 5L Model and Serial Numbers . .  . .  . .  . .  . .  . . 1-4
Figure 1-2 HP LaserJet 6L Model and Serial Numbers . .  . .  . .  . .  . .  . .  . 1-5
Figure 1-3 Front/Side Views of the Printer . .  . .  . .  . .  . .  . .  . .  . .  . . 1-7
Figure 1-4 Front Door Assemblies . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-8
Figure 1-5 Back View of the Printer . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-9
Figure 2-1 Printer Space Requirements . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 2-4
Figure 2-2 Toner Cartridge Distribution . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 2-6
Figure 3-1 Self-test Page for HP LaserJet 5L .  . .  . .  . .  . .  . .  . .  . .  . . 3-7
Figure 3-2 Self-test Page for HP LaserJet 6L .  . .  . .  . .  . .  . .  . .  . .  . . 3-8
Figure 3-3 Engine Test Button .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 3-10
Figure 4-1 Five Percent Text Coverage . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 4-4
Figure 4-2 Static Eliminator Teeth . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 4-8
Figure 5-1 Printer Functional Block Diagram .  . .  . .  . .  . .  . .  . .  . .  . . 5-3
Figure 5-2 DC Controller Loads . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 5-4
Figure 5-3 EconoMode vs Normal Mode .  . .  . .  . .  . .  . .  . .  . .  . .  . 5-10
Figure 5-4 Image Formation Block Diagram .  . .  . .  . .  . .  . .  . .  . .  . 5-12
Figure 5-5 Simplified Paper Path .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 5-16
Figure 5-6 Solenoid and Sensors .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 5-17
Figure 5-7 General Timing Diagram – HP LaserJet 5L . .  . .  . .  . .  . .  . 5-20
Figure 5-8 General Timing Diagram – HP LaserJet 6L . .  . .  . .  . .  . .  . 5-21
Figure 6-1 Phillips and Posidriv screwdrivers .  . .  . .  . .  . .  . .  . .  . .  . . 6-4
Figure 6-2 Back Cover Removal (1 of 2) .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-6
Figure 6-3 Back Cover Removal (2 of 2) .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-7
Figure 6-4 EP Door Assembly Removal .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-8
Figure 6-5 Memory Door Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-9
Figure 6-6 Main Cover and Paper Input Assembly Removal .  . .  . .  . .  . 6-10
Figure 6-7 Control Panel Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-11
Figure 6-8 Exit Roller Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-12
Figure 6-9 Delivery Assembly Removal (1 of 2) .  . .  . .  . .  . .  . .  . .  . 6-13
Figure 6-10 Delivery Assembly Removal (2 of 2) .  . .  . .  . .  . .  . .  . .  . 6-14
Figure 6-11 Fuser Pressure Plate Removal .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-15
Figure 6-12 Fuser Pressure Plate Replacement .  . .  . .  . .  . .  . .  . .  . .  . 6-16
Figure 6-13 Heating Element Removal (1 of 3) . .  . .  . .  . .  . .  . .  . .  . 6-17
Figure 6-14 Heating Element Removal (2 of 3) . .  . .  . .  . .  . .  . .  . .  . 6-18
Figure 6-15 Heating Element Removal (3 of 3) . .  . .  . .  . .  . .  . .  . .  . 6-19
Figure 6-16 Pressure Roller Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-20
Figure 6-17 Face-Up/Face-Down Lever Replacement .  . .  . .  . .  . .  . .  . 6-21
Figure 6-18 Fuser Exit Roller Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-22
Figure 6-19 Paper Exit Sensor Flag Replacement .  . .  . .  . .  . .  . .  . .  . 6-23
Figure 6-20 Laser/Scanner Assembly Removal . .  . .  . .  . .  . .  . .  . .  . 6-24
Figure 6-21 Solenoid Removal (1 of 2) .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-25
Figure 6-22 Solenoid Removal (2 of 2) .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 6-26
Figure 6-23 Pickup Roller Assembly Removal (1 of 2) . .  . .  . .  . .  . .  . 6-27
v 
						

							Figure 6-24 Pickup Roller Assembly Removal (2 of 2) .  . .  . .  . .  . .  . . 6-28
Figure 6-25 Paper Pickup Roller Assembly Replacement (Inside/Front View) 6-29
Figure 6-26 Paper Feed Frame Removal (1 of 4) . .  . .  . .  . .  . .  . .  . . 6-30
Figure 6-27 Paper Feed Frame Removal (2 of 4) . .  . .  . .  . .  . .  . .  . . 6-31
Figure 6-28 Paper Feed Frame Removal (3 of 4) . .  . .  . .  . .  . .  . .  . . 6-32
Figure 6-29 Paper Feed Frame Removal (4 of 4) . .  . .  . .  . .  . .  . .  . . 6-33
Figure 6-30 Transfer Roller Guide & Transfer Roller Removal
(Inside/Back View) .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-34
Figure 6-31 Kick Plate Removal .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-35
Figure 6-32 Kick Plate Spring Replacement .  . .  . .  . .  . .  . .  . .  . .  . . 6-36
Figure 6-33 Separation Pad Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-37
Figure 6-34 Subpad Removal .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-38
Figure 6-35 Feed Assembly Removal (1 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-39
Figure 6-36 Feed Assembly Removal (2 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-40
Figure 6-37 Feed Assembly Removal (3 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-41
Figure 6-38 Memory Door Guide Removal .  . .  . .  . .  . .  . .  . .  . .  . . 6-42
Figure 6-39 Motor Removal .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-43
Figure 6-40 DC Controller Removal (1 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-44
Figure 6-41 DC Controller Removal (2 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-45
Figure 6-42 DC Controller Removal (3 of 3) . .  . .  . .  . .  . .  . .  . .  . . 6-46
Figure 6-43 Formatter Board Removal . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 6-47
Figure 7-1 Paper Path and Components .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 7-5
Figure 7-2 DC Controller PCA Components . .  . .  . .  . .  . .  . .  . .  . .  . 7-6
Figure 7-3 Heating Element Resistance Check .  . .  . .  . .  . .  . .  . .  . . 7-11
Figure 7-4 Engine Test .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 7-21
Figure 7-5 Toner Cartridge High Voltage Connection Points (1 of 2) .  . . 7-24
Figure 7-6 Toner Cartridge High Voltage Connection Points (2 of 2) .  . . 7-25
Figure 7-7 Overriding PS204 and SW101 .  . .  . .  . .  . .  . .  . .  . .  . . 7-27
Figure 7-8 Repetitive Image Defect Ruler .  . .  . .  . .  . .  . .  . .  . .  . . 7-28
Figure 7-9 Repetitive Image Defect Ruler .  . .  . .  . .  . .  . .  . .  . .  . . 7-29
Figure 8-1 Major Assembly Locations .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-7
Figure 8-2 Covers and Doors . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-8
Figure 8-3 Internal Components (1 of 3) . .  . .  . .  . .  . .  . .  . .  . .  . . 8-10
Figure 8-4 Internal Components (2 of 3) . .  . .  . .  . .  . .  . .  . .  . .  . . 8-12
Figure 8-5 Internal Components (3 of 3) . .  . .  . .  . .  . .  . .  . .  . .  . . 8-14
Figure 8-6 DC Controller/Formatter and Cables . .  . .  . .  . .  . .  . .  . . 8-16
Figure 8-7 Pickup Roller Assembly .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-18
Figure 8-8 Feed Assembly .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-20
Figure 8-9 Separation Guide Assembly .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-22
Figure 8-10 Delivery Assembly .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-24
Figure B-1 VCCI Statement (Japan) . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . B-4
vi 
						

							List of Tables
Table 1-1 Printer Features . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-3
Table 1-2 Paper Capacities and Sizes . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-3
Table 1-3 Performance Specifications . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-6
Table 1-4 Electrical Specifications . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-6
Table 1-5 Acoustic Emissions . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-6
Table 1-6 Related Documentation . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-11
Table 2-1 Environmental Requirements .  . .  . .  . .  . .  . .  . .  . .  . .  . . 2-3
Table 2-2 Printer Dimensions . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 2-4
Table 3-1 Indicator Lights (1 of 2) . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 3-4
Table 3-1 Indicator Lights (Continued 2 of 2) . .  . .  . .  . .  . .  . .  . .  . . 3-5
Table 3-2 Front Panel Button Usage .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 3-6
Table 4-1 Life Expectancy of Consumables .  . .  . .  . .  . .  . .  . .  . .  . . 4-3
Table 4-2 Cleaning Printer Components .  . .  . .  . .  . .  . .  . .  . .  . .  . . 4-7
Table 5-1 Solenoid and Photosensors . .  . .  . .  . .  . .  . .  . .  . .  . .  . 5-17
Table 5-2 Printer Timing .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 5-19
Table 7-1 Printer Status Messages (1 of 2) . .  . .  . .  . .  . .  . .  . .  . .  . . 7-8
Table 7-2 Printer Status Messages (Continued 2 of 2) . .  . .  . .  . .  . .  . . 7-9
Table 7-3 Unclearable Error .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 7-9
Table 7-4 Service and Error Messages (1 of 3) .  . .  . .  . .  . .  . .  . .  . 7-10
Table 7-4 Service and Error Messages (Continued 2 of 3 ) .  . .  . .  . .  . 7-11
Table 7-4 Service and Error Messages (Continued 3 of 3) . .  . .  . .  . .  . 7-12
Table 7-5 High-Voltage Power Supply Check . .  . .  . .  . .  . .  . .  . .  . 7-24
Table 7-6 Paper Curl Troubleshooting . .  . .  . .  . .  . .  . .  . .  . .  . .  . 7-26
Table 7-7 Cable Pinouts .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 7-30
Table 7-8 Cable Pinouts .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 7-31
Table 8-1 Accessories and Supplies .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-5
Table 8-2 Common Fasteners Used in the Printer . .  . .  . .  . .  . .  . .  . . 8-6
Table 8-3 Covers and Doors .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 8-9
Table 8-4 Internal Components (1 of 3) .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-11
Table 8-5 Internal Components (2 of 3) .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-13
Table 8-5 Internal Components (3 of 3) .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-15
Table 8-6 ECU Case .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 8-17
Table A-1 Alphabetical Parts List .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . A-2
Table A-2 Numerical Parts Index .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . A-6
vii 
						

							viii 
						

							1
Product Information
Contents
Printer Features .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-3
Paper Capacities and Sizes . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-3
Identification .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-4
Model and Serial .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-4
Specifications . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-6
Product Overview . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-7
Front/Side Views of the Printer . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-7
Front Door Assemblies . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-8
Back View of the Printer .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . . 1-9
Service Approach . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-10
Parts Exchange Program .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-10
Ordering Parts . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-10
Ordering Consumables . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-10
Ordering Related Documentation . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-10
Technical Assistance . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-12
Worldwide Support . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-13
North American Response Center . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-13
Warranty .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-14
Warranty Exclusions .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-14
Warranty Limitations .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-15
Voltage Conversions .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . .  . 1-15
Product Information 1-1