External Assembly Locations (LaserJet 4L/4ML)

Figure 1-2

External Assembly Locations, Laserdef 4L/4ML
External Assembly Locations

(LaserJet 4P/4MP)

Internal Assembly Locations

Figure 1.4

Internal Assembly Locations (all printers) 10, Pickup Feed D-Roller 11. Transfer Roller Assembly 12, Photosensitive Drum
1, Face-Down Output Rollers 2. Upper Fusing Assembly 3. Laser/Scanner Assembly
4. Primary Charging Roller 5. Beam-to-Drum 7. Toner Cartridge 8. Registration Roller 9. Oblique Rollers Mirror
13. DC Controller PCA 14. Paper Cassette 15. Fusing Pressure Roller 16. Face-up Delivery Roller 17. Face-Up/Face-Down Deflector

6. Developing Cylinder

Fim.me 1-5 shows the location of assemblies visible from the ton of th; LaserJet 4L printer with the printer cover removed.

~lgure 1-5

LaserJet 4L Internal Assembly Locations 8. Fusing Assembly 9. Lower Output Rollers (Face-Down) 10. Upper Output Rollers (Face-Down) 11. Fan (FM1) 12. Beam-to-Drum 13. Laser/Scanner Mirror Assembly
1. Transfer Roller 2. Paper Guide/Top Oblique Roller 3. Front Oblique Roller 4, Switch Actuator 5. Formatter PCA m 6. Main Motor 7. Gear Train Assembly
Figure 1-6 shows the location of assemblies visible from the top of the LaserJet 4P printer with the printer cover removed.

Figure 1-6

LaserJet 4P Internal Assembly Locations 9. Fusing Assembly Oblique Roller 10. Lower Output Rollers (Face-Down) 11. Upper Output Rollers (Face-Down) 12. Fan (FM1) 13. Power Switch (not shown) 14, Beam-to-Drum 15, Laser/Scanner Mirror Assembly
1. Transfer Roller 2. Paper Guideflop
3. Front Oblique Roller 4. Cartridge Bracket 5. Formatter PCA 6. SIMM Slots (3) 7, Main Motor 8. Gear Train Assembly
Product Information Safety Information

Safety Information

Laser Safety
The Center for Devices and Radiological Health (CDRH) of the U.S. Food and Drug Administration implemented regulations for laser products manufactured since August 1, 1976. Compliance is mandatory for products marketed in the United States. This printer is certified as a Class 1 laser product under the U.S. Department of Health and Human Services (DHHS) Radiation Performance Standard according to the Radiation Control for Health and Safety Act of 1968. Since radiation emitted inside this printer is completely confined within protective housings and external covers, the laser beam cannot escape during any phase of normal user operation. Never operate or service the printer with the protective cover removed from the Laser/Scanner Assembly. The reflected beam, although invisible, can damage your eyes.

Laser Statement

(Finland)
The following applies to printer operation and servicing in Finland. LASERTURVALLISUUS LUOKAN 1 LASERLAITE KLASS 1 LASER APPARAT HP LaserJet(s) 4ML, 4P &. 4MP Iaserkirjoitin on kayttajan kannalta turvallinen 4L,

CAUTION

Toner Cartridge Handling Suggestions
Before installing a cartridge, distribute the toner evenly by rotating the cartridge back and forth five to six times (see Figure 2-2). Repeat this action when toner begins to run low.

Figure 2-2

Distributing Toner
Do not touch the sutiace of the photosensitive drum in the cartridge. Protect the drum from light and contamination. Do not disassemble or refill a toner cartridge, vibrations or shock.
Do not expose the cartridge to unnecessary
Do not expose the photosensitive drum to strong light. White areas on the page may indicate that the drum has been exposed to light for too long. If white areas appear, stop the printer and wait a few minutes. This process should eliminate most defective images, If not, the toner cartridge maybe placed in a dark environment for an extended period of time, which may restore some life to the drum. Never manually rotate the drum, especially in the reverse direction; internal damage and toner spills may result.
Operating Requirements The W 92274.4 Toner Cartridge
Refilled Toner Cartridges
While Hewlett-Packard does not prohibit the use of refilled toner cartridges during the warranty period or while under a maintenance contract, we do not recommend their use. The reasons for this are: Hewlett-Packard has no control or process to ensure that a refilled toner cartridge functions at the high level of reliability of a new HP LaserJet toner cartridge. Hewlett-Packard also cannot predict what the long term reliability effect on the printer is from using different toner formulations found in refilled cartridges. Hewlett-Packard has no control over the actual print quality of a refilled toner cartridge. The print quality of HP LaserJet toner cartridges influences the customers perception of the printer. Re~airs resultimz from the use of refilled toner cartridges are no{ covered und& the HP warranty or maintenance contract.

Recycling

Toner Cartridges
In order to reduce the amount of plastics and other wastes entering our landfllls, Hewlett-Packard has established a program for recycling used toner cartridges. Parts that do not wear are re-used in manufacture of new cartridges. Plastic and other materials are recycled. HP pays the shipping costs. In addition, a one dollar donation is shared by the Nature Conservancy and the National Wildlife Federation for each cartridge returned under this program. To join this recycling effort, follow the instructions included inside each toner cartridge box.

Operating Requirements Media Specifications

Media Specifications

Several types of print media can be used with HP LaserJet printers, provided the media specifications are met, Using media that does not meet the specifications listed in this section may increase the incidence of paper jams, cause premature printer wear, and contribute to repair costs. More detailed media specifications are available in the HP LaserJet Printer Family Paper Specification Guide, part number 5002-1801. To order additional copies, refer to Ordering Related Documentation in Chapter 1.
It is possible that print media can meet all of the general specifications listed and still not print satisfactorily because of the printing environment or other variables over which Hewlett-Packard has no control. Hewlett-Packard neither warrants nor recommends the use of any particular media brand. Properties are subject to change by manufacturers and HP has no control over such changes. The operator should test particular media prior to large purchases. All media should be stable at the 392 F / 200 C temperatures encountered in the printers fusing process. Use ordy media recommended for use in laser printers. Printer damage resulting from use of incompatible media will not be covered by HP warranty or service agreements.
Operating Requirements Media Specificatkms

Media Sizes Supported

The following media sizes are supported by the printers paper cassette and manual feed slot. -i-able2-3 Supported MediaS3zes LaserJet 4L/4ML Sizes Minimum size:* 3 x 7.5 in. (76x 190 mm) 3x5in. (76x 127mm) Letter, 8.5 x 11 in. (216x279 mm) LaserJet 4P/4MP Universal Cassette 7 Y Manual Feed
Legal, 8.5 x 14 in. (216x 356 mm) I Exec, 7.25 x 10.5 in. (184x 267 mm) A4, 210 x 297 mm (8,27 x 11.69 in.) Envelopes: Com-10, 4.1 x9.5 in. (105 x241 mm) Monarch, 3.87 x 7.5 in. (98x 191 mm) DL, 110 x220 mm (4.3 x 8.6 in,) C5, 162x 229 mm (6.4 x 9 in.)

-1x X1X x

X x r r r r I X x I

x x X1X x

r r x x x
Use the flat paper path only (manual feed and rear outpu

Caliper Curl Finishing Precision

Fusing Compatibility

Packaging
The flat paper path (manual feed slot and rear face-up delivery door) is recommended for printing adhesive labels.

Transparency

Overhead transparencies used in HP LaserJet printers must be able to withstand the 392 F (200 C) temperatures encountered in the printers fusing process for 0.1 second. Suitable transparency film is available through Hewlett-Packard. Refer to Chapter 3 of the HP LaserJet Printer Family Paper Specification Guide, HP Part No. 5002-1801 for details.
Caliper Cutting Angle Finishing precision
13.9 to 4.3 roils (0.100 to 0.110 mm) 90 * 0.2 Cut sheet to within 0.03 in. (0.8 mm) of nominal and t 0.2 of square. Overhead transparency material must be compatible with the heat and pressure of the fusing process. Materials must not discolor, melt, offset material, or release hazardous emissions when heated to 392 F (200 C) for 0,1 second.
The flat paper pat~ (manual feed slot and rear face-up delivery door) is recommended for printing transparencies.

Storing Print Media

Follow these guidelines when stacking and storing print media:
Store paper in its ream wrapper until ready to use. DO NOT store cartons or reams directly on the floo~ place cartons on a pallet or on shelves. DO NOT store individual reams in a manner that causes them to curl or warp along the edges. Re-wrap partially used packages of media before storing. DO NOT stack more than six cartons on top of each other. Stack each carton squarely on top of the one underneath. Stack each carton upright. DO NOT place anything on top of media, regardless the paper is packaged or unpackaged. of whether
Store envelopes in a protective box to avoid damaging the envelope edges. Keep stored media away from temperature extremes. and humidity
DO NOT store printed documents in vinyl folders (which may contain plasticizers) or expose the documents to petroleum based solvents.

Shipping Print Media

When shipping print media through different environments, plastic wrap all cartons on the shipping pallet. When shipping media across bodies of water, wrap individual cartons as well. Packaging must protect the media from physical damage.
Installation and Configuration
Installation and Configuration Unpacking and Installation
Unpacking and Installation
Before unpacking the printer, inspect the shipping container for signs of physical damage. Since a damaged shipping box is an indication of improper handling during shipping, the printer may also be damaged. If the shipping container has any sign of damage, unpack and power the printer ON with the carriers agent present. If the printer appears damaged or fails self test, do not accept it.

After veriffing the page count from the old Formatter it with the new PCA as described in Chapter 6. 1. Enter the Service Mode as described in this section. I[:E is 2. When fi~;~:.$ M[]CE displayed, press the the Service Menu.

key to access

key to step through the menu. ~HfiiIS=J@LKYX 3. Press the m is displayed.( ~ represents the page count currently stored in the printers Non-Volatile Memory. The underlined character denotes the cursor position. ) 4. Press the m digit. 5. Press the m 6. Press key to scroll the cursor to underline the desired
key to select the correct value. to store the new value in NVRAM. return the
7. Set each digit in the same manner. Press -to display to :%%~ICE WXE. 8. Press _ a second time to exit Service Mode.
Installation and Configuration service Mode (Laserdet 4MLMPMMP)
Setting the Cold Reset Default (LaserJet 4P/4MP)
The default paper size for Formatter PCAS in Europe is A4. When replacing Formatters whose default is set for A4, set the Customization Variable to A4. When the Customization Variable is set to A4, the Cold Reset procedure will always reset the paper size to A4 (not to Letter). To set the Customization Variable:
1. Enter the Service Mode as described in this section. 2. Press the key to access the Service Menu.
key to step through the menu until 3. Press the ~ ;-:;,7 r:_-. -i.:-,-.r:,-, m L,. , ,,, ,-, ~~, ,-.,.l,. L , -:-C;C> displayed. IS 4. Press the ~ 5. Press the ~ 6. Press -to 7. Press key to toggle between Letter and A4 paper. key to save your selection. return the display to :=ti:.~tii tififii:. a second time to exit Service Mode.

Other Service Mode Items

The other Service Menu items, z::! 2;?!H=: and ~:I:w%:3T I>;= are included for specialized purposes. If either item needs to be changed from the default setting (=%.: and :H%, respectively), s;: the procedure is similar to that used for setting the page count or Cold Reset default, described above.

Figure 3-8

Engine Test EWcm and Printout (LaserJet 4L shown]
Installation and Configuration Resetting the Printer

Resetting the Printer

Resetting the printer clears the printers memory, including unprinted data, downloaded fonts, and macros. It also removes some error conditions, and resets to factory default settings. The printer can be reset at any time, except when there is a service error condition.
1. Hold the front panel button down for at least five seconds. Release when all lights illuminate in succession from bottom to top. 2. After the printer has finished the reset, the Ready light comes on (if there are no printer errors).
The LaserJet 4P/4MP has several kinds of resets, as explained below. Simple Reset A simple reset does the following: Clears the printers page buffer. Removes all temporary typefaces and macros. Makes the current user-selected defaults active (making them the default values until you change them again). Purges the input buffer of the active 1/0 (the other I/O buffer is not affected).
To perform a simple reset: 1. Press_ to take the printer offline. The On Line light goes off and 2S ]H%i-Ii!~ appears on the display. 2. While holding down the ~ key, press briefly. Then the printer returns to 3. S7 ~~s~~ appears on the display. the on-line, 5E Z=W+ state.
The Menu of Resets Additional reset options are available through the Menu of Resets. Use the Menu of Resets option with caution. It can result in loss of buffered page data or printer configuration data. You should only use it when: You wish to restore the default printer settings. Communication between the printer and computer is interrupted. You are using both the serial and the ~arallel I/O ~orts. and one. of the ports ii having problems. To access the Menu of Resets: 1. Press to take the printer offline. 2. Hold down both the ~ and ~ keys for at least 10. seconds until ==:;:=-~=mw!appears on the display. 3. Use u or H to cycle through the items. to select your choice of resets. An asterisk * 4. Press ~ appears by the reset option. to execute the reset. 5. Press -
The foIlowing table shows the three reset options. Table 3-2

Menu Selection

Menu of Resets (LaserJet 4P/4MP)
Printer 09 MENU Response RESET Explanation

RESET.MENU

RESET=MENU restores most of the printers factory default settings. It also performs a simple reset. Items in the Config, Parallel, and Serial Menus are not reset, RESET=MENU clears only the active input buffer.

Printer Paper Path

Input Paper Sensor Input Paper Sensor (PSI ) Positions:
Paper Out Sensor Exit Paper Sensor Whaling Paper Sensor
A = Manual Feed Sense Position B = Registration Sense Position C = TOP Sense Position

Solenoids

Table 5-1 No. SLI SL2 Solenoids Name Paper Feed Solenoid (Registration) Pickup Solenoid Description Located in the Pickup Roller Assembly, and controls the registration rollers. Located on the DC Controller, and controls the Picku~ Feed D-Roller,

Photosensors

Table 5-2 Photosensors Name Psl PS2 Input Paper Sensor Paper Out Sensor Exit Paper Sensor Winding Paper Sensor

Description

Four-position photosensor. Senses manual feed and paper at registration position. Senses empty paper cassette, Senses paper exiting the fuser rollers. Senses paper in the paper feed guide area.

PS3 PS4

Paper Out Sensor (PS2)
The Paper Out Sensor (PS2) detects the presence of paper in the cassette. If no paper is sensed in the cassette, the Formatter displays the paper-out indication on the front panel (display panel message or Paper light). The cassette must be reloaded before printing can resume.

Input Paper Sensor (PSI)

The Input Paper Sensor, PSI, is a four position sensor that detects paper in the Manual Feed Sense Position, the Registration Position, and the Top Position. The figure to the left shows the Manual Feed and Cassette paper paths. The figures below show the sensor in each of the four positions.

Registration arm

The Ready or Wait/Standby Position indicates that paper has not entered the paper path.

@ WAIT (STBY)

Input Paper

Sensor (PSI )

The Manual Feed Sense Position (A) indicates that paper has either been inserted into the manual feed slot or has been picked from the paper cassette and reached this position in the paper path.
The Registration Position (B) signals the DC Controller to monitor if the scanner motor is up to speed and the fuser is at the correct temperature. When both conditions are met, the paper continues to the Top Position. If these conditions have not been met, solenoid SL1 is engaged to stop the registration roller until the printer is ready. When the printer is ready, SL1 disengages and paper proceeds to the Top Position.
The Top Position (C). When paper paeses through the Top Position, the DC Controller sends a signal to synchronize the image on the photosensitive drum with the top of the page.
Printing from the Paper Cassette
Paper motion begins when the DC Controller PCA, after receiving a PRINT signal, starts the Scanner Motor, the Main Motor, and the fusing heaters. The Pickup Solenoid (SL2) is energized for 0.5 seconds, the pickup roller and the registration roller rotate and feed a sheet of paper from the Paper Cassette to the Registration Position, where the registration roller is stopped by solenoid SL1, if necessary, until the Scanner and Fuser are ready. While the registration roller is rotating, the oblique rollers are aligning the papers left edge correctly to prevent skewing (see Figure 5-19).

5. Pull the Gear Train Assembly straight out to remove. Keep the gear side of the assembly face up (g=ars are held in place by light pressure only and may fall off if the assembly is tilted).

Figure 6-15

Removing the Gear Train Asswnbly (bswJet

4L shcwm)

LeffSide Assemblies
To re-instalh 1. Maneuver the assembly back in place, rotating some of the gears slightly to mesh, if necessary. 2. Tighten the screws beginning outward (Figure 6-16). in the center and working a CA!JTION Do not tighten the upper two Main Motor screws until the Main Motor and Gear Train are both in place. Tightening the screws without the Main. Motor in place can damage the mount.

Figure 6-16

Screw Tightening Sequence Example (Lase\rJei 4P shown)
1. Remove the Printer Cover, and the Formatter (Figure 6-17).

Shield and PCA

2. Remove the (1) machine screw through the access hole on the Gear Train Assembly, approximately two (2) inches below the top of the Main Motor (Figure 6-17, callout 1). 3. Remove the (2) self-tapping screws at the top of the Main Motor and pull the Main Mo{& s~raight up and out (Figure 6-17, callout 2).
Removal and Replacement Front Assemblies

Front Assemblies

Front Oblique Roller Assembly
The Front Oblique Roller Assembly is located on the front of the printer, and is accessible after removing the Paper Cassette. It can be removed without removing the Printer Cover. 1. Remove the Paper Cassette. 2. Remove the (1) self-tapping screw on the left of the Front Oblique Roller Assembly and tilt the assembly out at the bottom to remove (Figure 6-18, callout 1).

Figure 6-l El

Removing the Oblique Roller Assembly

Paper Cassette Assembly

Field replaceable parts on the Universal Paper Cassette include: the Tray Forms Size Guide(s), two compression springs. Tray Forms Size Guide (LaserJet 41J4ML) Note The forms size guides on the LaserJet 4P/4MP are very easily removed and are not shown here.
1. Remove the Paper Cassette from the printer and unload paper. 2. Slide the guide all the way to the left and forward (near the B5 adjustment line).
3. Lift the inside corner up slightly while twisting the guide in a clockwise direction. This frees the tab on the back side of the cassette, allowing removal.

Figure 6-19

Rwmvkj theTray Forms Size Guide (LaserJet 4L/4ML shown)
Compression Springs The Paper Cassette compression springs are located under the large pressure plate. The LaserJet 4L/4ML is shown here. Removal procedures for the LaserJet 4P/4MP are very similar. 1. Remove the Paper Cassette from the printer and unload paper. 2. Release the plastic latch on the lower left corner of the cassette assembly (Figure 6-20). Rotate the metal bar up and out of the way.

5. Worn or broken drive gears. If any gear within the drive train or paper path becomes excessively worn or dirty, erratic paoer movement can result, 6. Worn Pickup, Oblique, and/or Registration Rollers. Paper is not being picked-up consistently.
Inspect all paper path rollers, looking for ~ear, cracks, or glazing. Replace the ~orn rollers.

Table 7-31

Smeared Print POSSIBLE CAUSE RECOMMENDED ACTION ,0
1, Bad media. The moisture content, con- Try a different paper lot or other media (see Media Specifications in Chapter 2). ductivity, or surface finish of the media being printed may not work correctly with the electrophotographic process.
2. Dirty Fusing Rollers. Toner build-up can cause the print on a page to smear. 3. The Static Eliminator Strip is dirly or is not grounded, allowing a static charge to remain on the page. 4. Fusing Assembly is defective. The print will smear if the Fusing Assembly is not heated sufficiently to bond the toner image to the paper. 5. DC Controller is defective. The DC Controller regulates fusing roller temperature.
Remove and inspect the Fusing Assembly for excessive toner build-up. Clean using alcohol. Clean or replace the Static Eliminator Strip, Usecompressed airtoclean (see Static Eliminator Strip in Chapter 6). Replace the Fusing Assembly,
If a new Fusing Assembly does not resolve the problem, replace the DC Controller PCA.

Table 7-32

Imaae Skew POSSIBLE CAUSE RECOMMENDED ACTION
1. Paper is loaded incorrectly. If the paper is not installed flush into the paper cassette, a skewing problem will result. 2. Bad Paper Lot. Paper that is manufactured poorly or inconsistently, or that has too smooth or too rough a surface texture can cause an imaqe skew problem.
Remove paper from the tray and install paper correctly. Position the paper guide correctly for the paper size being used. Try a different paper lot (see Media Specifications in Chapter 2).
3. Worn Pickup, Oblique, and/or Registra- Inspect all paper path rollers, looking for tion Rollers. Paper is not being picked-up wear, cracks, or glazing. Replace the worn rollers. consistently. 4. Beam-to-Drum Mirror adjustment is required. If the mirror has been removed, or the right end mounting screw has been loosened, the mirror needs to be readjusted. 5. Manual feed skew problems. Refer to (Beam-to-Drum Mirror adjustment, later in this chapter to adjust the image to proper tolerances.
Instruct customer to feed media against left side alignment guide, and not to reinsert once the printer grips the media.

Table 7-33

Compressed

Print RECOMMENDED ACTION

POSSIBLE CAUSE 1Toner carlridge bushings are too tight. This may occur on refilled toner cartridges. 2. Broken or worn gear.
Replace the toner cartridge.
Inspect and replace the worn gear or assembly.
Troubleshooting Engine Test
The engine test print is used to verify that the print engine is functioning correctly. The Formatter PCA is completely bypassed during an engine test. This testis therefore very useful for isolating printer problems. The engine test prints a full page of vertical lines down the entire printable area, and is thus also useful for checking and adjusting registration.
Engine Test Button Location
The engine test print button(SW301) is located on the side of the DC Controller PCA (see Figure 7-2). It is accessible through a hole in the Gear Train plate.
Printing an Engine Test - LaserJet 4L/4ML
On the LaserJet 4L/4ML, the engine test button is accessible without removing the covers, through the I/O Door area on the left side of the printer. To print an engine test, use a long object (such as a pencil) to press the engine test button (see Figure 7-4). (Do not use a metal object.) A single test page is printed.

gure 7-4

Engine Test Button and Printout, LaserJet 4L/4ML
Printing an Engine Test - LaserJet 4P/4MP
On the LaserJet 4P/4MP, the printers covers and the Formatter PCA must be removed prior to printing an Engine Test. Since the covers will be removed, the printers safety interlocks must be defeated to provide power for running the Engine Test. To defeat the interlocks and set-up the printer for an Engine Test: Shield and the
1, Remove the printer cover, the Formatter Formatter PCA (see Chapter 6).
2. Install the paper cassette (with paper loaded). 3. Install a toner cartridge in the ptinter. Lay a large sheet of thick paper over the toner cartridge and Laser/Scanner Assembly to block out ambient room light (this will prevent black streaks on the printed output). 4. On the to~ of the winter, Top DoorPlunge;(sho~ use a ~iece of tape to hold down the in Fi&e 7-5). -

/~{l$$;~;%l%wn

even with chassis TOEIRail to defeat.)

A$~inbly

Figure7-5
Defealing Top Ek90r h,mgw (Law!kfi the P
5. On the rear of the Fusing Assembly, use a pencil or flat-blade screwdriver to press the flag mechanism for the Exit Paper Sensor (PS3) in just until it is about flush with the face of the fuser (see Figure 7-6). Do not push the PS3 flag in more than about 1/8 inch (3 mm). If PS3 is pressed in too far, the printer will register a power-on jam and the Engine Test will not print. If this occurs, decrease the depth of the PS3 flag, power-cycle the printer, then retry the Engine Test.

8-6 8-5 8-5 8-3 8-5 8-6 8-2 8-3 8-6 8-10 8-9 8-3 8-3 8-3 8-2 8-3 8-2 8-3 8-2 8-3 8-7 8-4 8-4 8-7 8-7 8-7 i 8-7
Bezel Assembly, LJ 4P/4MP Bushing Bushing, D-roller Button, Lock, LJ 4U4ML Button, Lock, LJ 4P/4MP Cap, Laser Shutter Claw, Separation Claw, Separation Control Panel Assembly, LJ 4P/4MP Control Panel PCA, LJ 4P/4MP Cover Assembly, LJ 4P/4MP Cover Assembly, LJ 4U4ML Cover, Font, LJ 4P/4MP Cover, Main, LJ 4U4ML Cover, Main, LJ 4P/4MP CRG Pressure Piece, LJ 4U4ML CRG Pressure Piece, LJ 4P/4MP DC Controller Case Assembly DC Controller Connector, LJ 4U4ML DC Controller Connector, LJ 4P/4MP DC Controller PCA, 100-1 20V, LJ 4U4ML (Exchange) DC Controller PCA, 100-1 20V, LJ 4U4ML (New) DC Controller PCA, 100-120V, LJ 4P/4MP (Exchange) DC Controller PCA, 100-120V, LJ 4P/4MP (New)

Parts Index-2

DESCRIPTION DC Controller PCA, 220-240V, LJ 4L/4ML (Exchange) DC Controller PCA, 220-240V, LJ 4L/4ML (New) DC Controller PCA, 220-240V, LJ 4P/4MP (Exchange) DC Controller PCA, 220-240V, LJ 4P/4MP (New) Display Cable, LJ 4P/4MP Door, Back Assembly, LJ 4L/4ML Door, Back Assembly, LJ 4P/4MP Door, I/O, LJ 4L/4ML Door, Memory, LJ 4U4ML Door, Power, LJ 4U4ML Door, Top, LJ 4L/4ML Door, Top, LJ 4P/4MP Drive Gear, LJ 4P/4MP Dust Cover, Foam Rubber E-Clip, LJ 4L/4ML E-Clip, LJ 4P/4MP Fan Assembly Flaq, Exit Sensor Font Door Plug, LJ 4MP only Font Guidej LJ 4P/4MP Foot, Chassis Formatter PCA, LJ 4L (Exchange) Formatter PCA, LJ 4L (New) Formatter PCA, LJ 4ML (Exchange) Formatter PCA, LJ 4ML (New) Formatter PCA, LJ 4MP (Exchange) Formatter PCA, LJ 4MP (New) Formatter PCA, LJ 4P (Exchange) Formatter PCA, LJ 4P (New)
PART NUMBER C2003-69004 RG5-0767-OOOCN C2005-69004 RG5-0823-OOOCN RG5-0815-OOOCN RG5-0691 -OOOCN RG5-0691 -OOOCN RB1 -2977-OOOCN RBI -2979-OOOCN RBI -2978-OOOCN RB1 -3129-OOOCN RBI -3332-OOOCN RS5-0364-OOOCN RB1 -3392-OOOCN XD2-1 100-242CN XD2-I 100-242CN RG5-0703-OOOCN RBI-3097-OOOCN C2040-40002 C2005-00004 RB1 -3001 -OOOCN C2004-69001 C2004-67901 C2016-69001 C2016-67901 C2041-69001 C2041 -67901 C2006-69001 C2006-67901
I FIG I 8-7 8-7 8-7 8-7 8-3 8-2 8-3 8-2 8-2 8-2 8-2 8-3 8-6 8-6 8-2 8-3 8-4 8-12 8-3 8-4 8-6 I 8-4 8-4 8-4 8-4 8-4 8-4 8-4 8-4

Parts Index-7

DESCRIPTION Spring, Leaf, LJ 4U4ML Sprino, Leaf, LJ 4P/4MP
PART NUMBER RBI -3125-OOOCN RB1 -3402-OOOCN

FIG 8-8 8-8

Parts Index-8
Parts Index Numerical Parts Index

arts Index

DESCRIPTION Screw, washer-head, Screw, washer-head, 1252-5460 C2003-00005 C2003-00032 C2003-40001 C2003-69001 C2003-69002 C2003-69003 C2003-69004 C2003-69005 C2004-67901 C2004-69001 C2005-00001 C2005-00004 C2005-00013 C2005-40001 short (8 mm) long (12 mm) FIG 8-4 8-4 8-4 8-4 8-2 8-4 8-4 8-12 8-12 8-7 8-7 8-6 8-4 I 8-4
DC Controller Connector, LJ 4L/4ML DC Controller Connector, LJ 4P/4MP Nameplate, LJ 4L RFI Shield, LJ 4L Switch Acutuator, LJ 4UML Fuser Assembly, 100-120V (Exchange) Fuser Assembly, 220-240V (Exchange) DC Controller PCA, 100-120V, LJ 4U4ML (Exchange) DC Controller PCA, 220-240V, LJ 4L/4ML (Exchange) Laser/Scanner Assemblv, LJ 4U4ML (Exchange) Formatter PCA, LJ 4L (New) Formatter PCA, LJ 4L (Exchange) Nameplate, LJ 4P Font Guide, LJ 4P/4MP RFI Shield, LJ 4P/4MP l/O Cover Plate, LJ 4P KeVboard Overlay, Euro-English Keyboard Overlay, Turkish Kevboard Overlav, Portuguese C2005-40005 Keyboard Overlay, German Keyboard Overlay, Spanish Keyboard Overlay, French Keyboard Overlay, Italian Keyboard Overlay, Dutch Keyboard Overlay, Norwegian
C2005-40006 C2005-40007 C2005-40008 C2005-40009 C2005-4001 O

Parts Index-9

Numerical Parts Index
PART NUMBER C2005-40011 C2005-40012 C2005-40013 C2005-40014 C2005-40017 C2005-40018 C2005-69003 C2005-69004 C2005-69005 C2006-67901 C2006-69001 C2015-00001 C201 5-00002 C2015-00003 C2016-67901 C2016-69001 C2040-00001 C2040-40001 C2040-40002 C2041 -67901 C2041 -69001 R75-001 O-OOOCN R75-201 O-OOOCN RBI -2971 -OOOCN RB1 -2974-OOOCN RBI -2976-OOOCN RB1-2977-OOOCN RBI-2978-OOOCN RBI-2979-OOOCN
DESCRIPTION Keyboard Overlay, Polish Keyboard Overlay, Swedish Keyboard Overlay, Finnish Keyboard Overlay, Danish Keyboard Overlay, Chinese Keyboard Overlay, Taiwanese DC Controller PCA, 100-120V, LJ 4P/4MP (Exchange) DC Controller PCA, 220-240V, LJ 4P14MP (Exchange) Laser/Scanner Assembly, LJ 4P/4MP (Exchan~e) Formatter PCA, LJ 4P (New} Formatter PCA, LJ 4P (Exchange) Nameplate, LJ 4ML RFI Shield, LJ 4ML RFI Shield, LJ 4ML, Mini DIN Formatter PCA, LJ 4ML (New) Formatter PCA, LJ 4ML (Exchange) Nameplate, LJ 4MP l/O Cover Plate, LJ 4MP Font Door Plug, LJ 4MP only Formatter PCA, LJ 4MP (New) Formatter PCA, LJ 4MP (Exchange) Universal Paper Cassette, LJ 4U4ML Universal Pa~er Cassette, LJ 4P14MP Bushing, D-roller Plate, Gear Plate Ground Light Pipe, LJ 4U4ML Door, 1/0, LJ 4U4ML Door, Power, LJ 4U4ML Door, Memory, LJ 4U4ML

Index-2

Irick?x
front panel button clearing error states 3-10 overview 3-9 resuming after memory error 3-10 usage table 3-11 functions, basic printer (theory) 5-2 fuser error (50 SERVICE) 7-12 fuses, DC Controller 6-42 Fusing Assembly 6-30 fusing stage (theory) 5-32 G Gear Train Assembly 6-17
J Japanese VCCI Statement
H half self test functional check 7-39 hardware, common 8-4 help labels 3-6 help labels installation 3-6 high speed, parallel I/O (theory) 5-14 High Voltage Connector Assembly 6-42 high voltage distribution (theory) 5-11 high-voltage power supply check 7-41 HP ASAP (Automated Swmort Access Program) 1-20 HP AUDIO TIPS 1-21 HP Explorer drivers disk, using 3-8 HP FIRST (Fax Information Retrieval Support Technology) 1-20
L laser and scanner drive (theory) 5-5 laser statement, Finland 1-12 Laser/Scanner Assembly 6-23 leading edge adjustment 7-43 LEDs 3-10 left side assemblies 6-15-6-29 life expectancy of consumables 4-3- 4-5 lights, room (flickering effect) 2-2 lights (LEDs), functions 3-10 loading the paper cassette 3-4 LocalTalk feature 1-2 LocalTalk cabling information B-4 - B-6 LocalTalk 1% (theory) 5-15 Lower Output Rollers 6-38 M Main Motor 6-16 main motor error (57 ERROR) 7-15 main motor (theory) 5-7 main wiring diagram 7-47-7-48 maintenance 4-1-4-12 Manual Feed mode control panel message 3-10 manual feed printing (theory) 5-38 Material Safety Data Sheet (MSDS) 1-14 matrix, printer features 1-2 media selection guidelines 2-10 media specifications 2-8-2-16 memory configuration 3-21 Memory Door 6-6 memory enhancement technology (MEt) (theory) 5-19 memory error control panel message 3-10 memory management (theory) 5-19 memory upgrade 6-4 when needed 3-10 memory, standard & optional 1-2 memoryflanguage SIMMS 6-5 menu of resets 3-27 monthly usage 1-2 motors (theory) 5-7 MSDS 1-14 N non-volatile memory (NVRAM) (theory) 5-14 NVRAM error (68 ERROR) 7-12 NVRAM Reset 7-17
UO Door 6-6 identification, printer 1-3 Image Adapt (theory) 5-20 image formation (theory) 5-22-5-32 troubleshooting 7-19-7-35 image skew adjustment 7-44 indicator lights 3-10 Input Paper Sensor, PS 1 (theory) 5-36 Input Paper Sensor Arm 6-56 input trays 1-2 intelligent on/off (theory) 5-10 installation and configuration 3-1-3-30 help labels 3-6 power cord 3-5 printer 3-2 -3-8 printer drivers 3-7 toner cartridge 3-3 interface cables, attaching 3-4, B-4 - B-6 internal assemblies 6-23-6-29 internal assembly locations 1-8

Troubleshooting Engine Test

Engine Test

The engine test print is used to verify that the print engine is functioning correctly. The Formatter PCA is completely bypassed during an engine test. This testis therefore very useful for isolating printer problems. The engine test prints a full page of vertical lines down the entire printable area, and is thus also useful for checking and adjusting registration.
Engine Test Button Location
The engine test print button(SW301) is located on the side of the DC Controller PCA (see Figure 7-2). It is accessible through a hole in the Gear Train plate.
Printing an Engine Test - LaserJet 4L/4ML
On the LaserJet 4L/4ML, the engine test button is accessible without removing the covers, through the I/O Door area on the left side of the printer. To print an engine test, use a long object (such as a pencil) to press the engine test button (see Figure 7-4). (Do not use a metal object.) A single test page is printed.

gure 7-4

Engine Test Button and Printout, LaserJet 4L/4ML
Printing an Engine Test - LaserJet 4P/4MP
On the LaserJet 4P/4MP, the printers covers and the Formatter PCA must be removed prior to printing an Engine Test. Since the covers will be removed, the printers safety interlocks must be defeated to provide power for running the Engine Test. To defeat the interlocks and set-up the printer for an Engine Test: Shield and the
1, Remove the printer cover, the Formatter Formatter PCA (see Chapter 6).
2. Install the paper cassette (with paper loaded). 3. Install a toner cartridge in the ptinter. Lay a large sheet of thick paper over the toner cartridge and Laser/Scanner Assembly to block out ambient room light (this will prevent black streaks on the printed output). 4. On the to~ of the winter, Top DoorPlunge;(sho~ use a ~iece of tape to hold down the in Fi&e 7-5). -

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even with chassis TOEIRail to defeat.)

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Figure7-5
Defealing Top Ek90r h,mgw (Law!kfi the P

4P/4MP)

5. On the rear of the Fusing Assembly, use a pencil or flat-blade screwdriver to press the flag mechanism for the Exit Paper Sensor (PS3) in just until it is about flush with the face of the fuser (see Figure 7-6). Do not push the PS3 flag in more than about 1/8 inch (3 mm). If PS3 is pressed in too far, the printer will register a power-on jam and the Engine Test will not print. If this occurs, decrease the depth of the PS3 flag, power-cycle the printer, then retry the Engine Test.
6. Plug the ac power cord into the printer. 7. Exert downward pressure on the the toner cartridge (through the light-blocking paper) while pressing the Engine Test button SW301. Use a pencil or other non-metallic object to reach through the access hole in the Gear Train plate (similar to that shown in Figure 7-4). 8. If the single page Engine Test does not print, power-off the printer, check the Top Door Plunger to be sure it is held all the way down (step 4), and adjust the depth of the Exit Paper Sensor flag as described in step 5. 7-38