HP Laserjet 4 Manual

For further information on interval dimensions, refer to the
Repetitive Defect Ruler, Figure 7-19.
Possible Cause Action
Toner Cartridge. The circumference of
the photoconductive drum is 3.75 inches
(94mm). The circumference of the
developer roller is 2 inches (51mm). If a
defect appears in the print image at
these intervals, assume the defect is
associated with the Toner Cartridge.Replace the Toner Cartridge.
Fuser Assembly. The Fuser Roller’s
circumference is approximately
2.5 inches (63mm) for the...

Possible Cause Action
Fuser levers not in place.
(All LJ4, some LJ4+, N/A on LJ5)The Fuser Assembly has shipping levers
that must be lowered during the setup
process. See Chapter 3 for instruction on
how to lower the fusing levers.
Media. The media may not be acceptable
for laser printing. Heavy paper stock is a
common cause of smeared print and
improper fusing.Verify that the media meets
specifications as shown in the HP
LaserJet Family Paper Specifications
Guide.
Dirty Fuser Assembly. The print smears...

Possible Cause Action
Laser/Scanning Assembly or DC
Controller PCA.Replace the Laser/Scanning Assembly
followed by the DC Controller PCA, if
necessary (see Figure 7-12 for locations).
Table 7-22Black Pages with Horizontal White Strips
Possible Cause Action
Input/Registration Sensor (PS1). The
Paper Pickup Roller positions the leading
edge of the paper at the
Input/Registration Sensor (PS1). If this
sensor is defective it may not sense the
presence of the paper reliably (on time).Replace the...

PS5 Check (MP Tray Paper End Sensor) Functional Test 
1Make a test sheet by cutting a notch in the trailing edge of a
sheet of paper as shown in Figure 7-9. 
2Perform the set up procedures listed for the PS4 check (MP
Tray Empty Sensor) on page 7-17, and put the test sheet into
the MP tray when the display reads XX LOAD LEGAL.
3The self test print should stop 2 to 5 mm above the notch (see
Figure 7-9). 
4Print that extends into cut out area indicates that the sensor
PS5 is not free in its travel or is...

Figure 7-9 PS5 Test Sheet
Troubleshooting 7-45 

Possible Cause Action
Dirty Primary Charge roller. Change the Toner Cartridge.
Bad Toner Cartridge. Replace the Toner Cartridge.
Incompatible media. During media
manufacture, inks, or other finishing
processes may interfere with the
electro-photographic or fusing process.Change type of media.
Table 7-25Vertical Dark Streaks 
Possible Cause Action
Defective laser shutter. Check the laser shutter for free operation
when inserting the EP Toner Cartridge.
EP Cartridge Support damaged,
improperly positioned,...

Possible Cause Action
Defective Toner Cartridge. The Toner
Cartridge may be internally damaged.Replace the Toner Cartridge.
Bad paper lot. The paper moisture
content, conductivity, or surface finish
may be incompatible with the
electro-photographic process.Try a different paper lot (see the HP
LaserJet Family Paper Specifications
Guide) for paper specifications.
Print density set incorrectly. If the print
density is set incorrectly, background
scatter can result, particularly with
envelopes.Adjust the...

Possible Cause Action
Defective laser shutter. Check the laser shutter for free operation
when inserting the EP Toner Cartridge.
EP Cartridge Support damaged,
improperly positioned, or missing.Refer to item 4 in Figure 8-4a.  Guide
must be installed properly above the EP
Cartridge, between the laser shutter
opening and the fuser stop plate.
Toner Cartridge. No toner is available for
print.Remove sealing tape or replace the
Toner Cartridge.
No Transfer Roller voltage. Without
transfer charge roller...

Image Formation Troubleshooting
Half Self-Test Functional Check  
The electro-photographic process can be subdivided into the
following stages: 
•Cleaning (Physical and Electrostatic).
•Conditioning (Primary Charge Roller).
•Writing (Laser Modulation).
•Development (Formation of the Toner Image).
•Transfer (Charge to transfer the image to paper).
The purpose of the Half Self Test Check is to determine which
process is malfunctioning.  Perform the test as follows:
1Initiate an 05 SELF TEST. 
2Open or...

Drum Rotation Functional Check 
The photoconductive drum, located in the Toner Cartridge, must
rotate for the print process to work.  The photoconductive drum
receives its drive from the Main Motor gear train.  To verify
whether the drum is rotating:
1Open the printer’s Top Cover Assembly.  
2Remove the Toner Cartridge.  Open the Toner Cartridge’s
drum shield (cover) to view the photoconductive drum.
3Mark the gear with a felt-tipped marker.  Note the position of
the mark.
4Install the EP Toner...