HP 4 Plus Manual

							51 ERROR Message  
The 51 ERROR, and the 41.2 ERROR  are caused by Beam Detect
failures. If the beam detect signal is lost for more than 2 seconds
the error is posted as a 51 ERROR . The 41.2 ERROR  can be cleared
by pressing  [Continue] (or Go). The  51 ERROR  may be cleared by
power cycling the printer.
Figure 7-6 Fuser Assembly Connector
Checks Action
1. Are all connectors on the DC
Controller properly seated? Inspect connectors and wiring. Reseat or
replace cables if necessary.
2. Is the Laser/Scanner Assembly
Defective? A defective Laser/Scanner Assembly can
cause a
 51 ERROR by spinning the
scanning mirror at the wrong speed.
Replace the Laser/Scanner Assembly.
3. Is the DC Controller Defective? Replace the DC Controller.
4. Has the printer been moved from a
cold to a warm room? Allow the printer to stand 6 hours until
any condensation has dissipated.
Table 7-1151 ERROR Beam Detect Checks
Troubleshooting 7-31 
						

							52 ERROR Scanner Malfunction  
The scanner motor is a flat, brushless, DC motor. Motor operation
is completely controlled by the DC Controller.  
The scanner motor is enabled when the printer is powered-up
(during the printer’s power-on self test), or whenever the PRINT
command is received by the Formatter PCA.  The scanner motor
makes a distinctive sound when starting.  The sound can be
described as a  “variable pitch whirring ” sound.  Listen for the
sound of the scanner motor when troubleshooting the  52 ERROR.  
Laser/Scanner Assembly Functional Checks 
Initiate a Self Test.  As the test begins, listen for the sound of the
scanner motor. If the motor cannot be heard, perform the
following in the order given:
1Check the Laser/Scanner and the Power Supply cables.
Replace if necessary. 
2Replace the Laser/Scanner Assembly.  
3Replace the DC Controller. 
7-32 Troubleshooting 
						

							57 (or 57.1) SERVICE Message (Main Motor
Fa i l u r e )   
The 57 SERV\fCE indicates that the DC Controller PCA detected a
general motor failure. The Main Motor drives all moving
components in the printing process. The Main Motor is a 4-phase,
DC servo motor controlled by the DC Controller PCA. 
The formatter detects a Main Motor failure when:
•The Main Motor does not come up to speed within one second
of receiving drive voltage.
•The Main Motor deviates from the correct speed for one second
after reaching the correct speed.
Main Motor Functional Checks    
•Inspect the gear train for debris that would block the free
operation of the gears.
•Check the gears in the Toner Cartridge for wear and binding.
•Reseat J211 (or J214 on the HP LaserJet 4 Plus/4M Plus) on
the DC Controller PCA, and the main connector on the Main
Motor Assembly. Refer to Figures 7-16 and 7-17 for the DC
Controller PCA connector locations. 
•If the problem persists, check that the +24B Voltage is present
on the DC Controller. If the voltage is not present, replace the
DC Controller. If the voltage is present, and the motor does
not rotate, replace the Main Motor Assembly (see Figure 7-11
for location).
Troubleshooting 7-33 
						

							58 (or 57.2) SERVICE (Fan Failure)     
The 58 SERV\fCE indicates that the DC Controller detected a
failure in the Exhaust Fan (FM1) in  the printer or the optional
duplexer.  When troubleshooting this problem, perform the
following steps in the order given.
1Check that the fan is mounted correctly in its shroud.
2Check that the fan blades are not blocked.
3Check that the Cooling Fan connector is firmly seated on the
DC Controller (see Figure 7-16 or Figure 7-17 for location).
If the above checks are satisfactory, replace the fan.
Note Verify the direction of air flow. Air should blow
out of the printer.
7-34 Troubleshooting 
						

							Image Defect Summary               
The quality of the printer’s output is subject to the judgment of
the user.  This section of the manual helps you define print
quality defects, and understand what factors affect print quality.
The print samples shown in the following figures illustrate some
print quality defects.  Keep copies of print quality defects
encountered in the field with an explanation of their causes for
future reference.
The image defects listed below are covered in the following tables.
(For major assembly, connector, and switch locations, see Figures
7-11 through 7-18 later in this chapter.)
•Black Pages.      
•Any Faint Print Condition
•Faulty Registration
•Vertical White Streaks.    
•Right-hand Image Missing.    
•Small Print Voids
•Random Horizontal Black Lines
•Repetitive Defects.       
•Smeared Print/Improper Fusing.
•Distorted Print.
•Black Pages with Horizontal White Strips.
•Image Skew.
•Improperly Sized Image.
•Vertical Dark Streaks.
•Large Print Voids.
•Background Scatter.
•White or Blank Pages.
Troubleshooting 7-35 
						

							Figure 7-7 Image Defect Summary
7-36 Troubleshooting 
						

							Figure 7-8 Image Defect Summary
Troubleshooting 7-37 
						

							Possible CauseAction
The HVPS connections are dirty. Clean the HVPS terminals (see Figure
7-18 for layout).
The HVPS is installed improperly. If the
HVPS has been removed and replaced,
it may not be seated properly. Remove the HVPS, and check the
connectors for damage. Reseat the
HVPS, being certain to fully seat the
connectors.
Bad Primary Charging Roller. Replace the Toner Cartridge.
The HVPS is defective. Replace the HVPS.
DC Controller PCA. The laser drive
circuitry is damaged so that the laser is
always on. Replace the DC Controller PCA, followed
by the Formatter PCA if required.
Table 7-12Black Pages
Possible Cause
Action
Printer set to Economode. Change driver and/or Control Panel
settings to ECONOMODE=OFF.
Toner Cartridge. Replace the Toner Cartridge.
Print density set improperly. The higher
the print density setting, the more toner
transferred to the drum. Set the print density to a darker level.
Replace the high voltage power supply if
this has no effect.
The paper finish, conductivity, or
moisture content may not be suitable for
the electro-photographic printing process. Try a known good source of paper from a
freshly opened package. Refer to the HP
LaserJet Family Paper Specifications
Guide for media specifications.
The transfer roller may be defective. Replace or reseat the roller.
Weak or no developer bias. If
inadequate, or no developer bias is
produced, toner is not attracted to the
image written on the drum. Adjust the print density setting as shown
in Chapter 3. 
Table 7-13Any Faint Print Condition
7-38 Troubleshooting 
						

							Possible CauseAction
Paper. The surface of the paper may be
too smooth for the pickup roller to move
the paper through the paper path. Change paper. Try a brand of paper
known to be good.
Worn Pickup Roller and Separation Pad. If the Paper Pickup Roller, or the Separation Pad are sufficiently worn, the
leading edge of the paper may not reach
the registration assembly in time.
Replace the Pickup Roller and
Separation Pad together.
PS1 faulty. If the Input/Registration
sensor (PS1) is broken, it can not sense
the presence of paper at the registration
point. Replace the Input/Registration Sensor.
Drive Gears. If any gear within the gear
drive train becomes excessively worn or
dir ty, erratic paper movement results,
causing image misregistration. Examine the gears along the paper path
for wear and contamination. Clean and
inspect the gears. Replace any broken or
defective gears.
Paper Tray. The paper tray may be
preventing the paper from moving
through the printer. Verify that the tray is loaded correctly.
Verify that the paper tray is seated fully
into the printer. If possible, exchange tray
with another printer to see if the problem
is associated with the tray. Note the HP
LaserJet 4/4M tray is NOT
interchangeable with the HP LaserJet 4
Plus/4M Plus tray. The LJ5 paper trays
are not compatible with the LJ4 or LJ4+.
Replace the paper tray.
DC Controller replaced. If the DC Controller was replaced, adjust VR202 as shown in Chapter 6.
Paper Input Assembly replaced. The HP LaserJet 4/4M Paper Input Assembly is NOT compatible with the HP
LaserJet 4 Plus/4M Plus.  The LJ5 Paper
Input Assembly is not compatible with the
LJ4 or LJ4+ Input Assemblies. Installing
a non-compatible Input Assembly results
in paper input registration problems.
Table 7-14Faulty Registration
Troubleshooting 7-39 
						

							 
Possible CauseAction
No toner available for print. Shake/replace the EP Toner Cartridge.
Laser shutter may be blocking the beam Ensure that the mechanism that lifts the shutter is functional, for example, the
shutter doesn’t stick in its travel, and is
lifted evenly. 
Table 7-15Right-Hand Image Missing 
Possible Cause Action
Small voids on black, or near-black
printed images may be caused by
imbedded toner on the
electro-photographic drum. Cartridges
that are run for long periods of time in
high temperature and humidity conditions
may develop this problem. Replace the EP Toner Cartridge. If the
printer is installed in a hot or humid
location, tell the customer to move the
printer to a better location.
Table 7-16Small Print Voids 
Possible Cause
Action
Laser/Scanning Assembly misaligned or
damaged. Replace the Laser/Scanner Assembly.
DC Controller PCA Replace the DC Controller PCA.
Table 7-17Random Horizontal Black Lines  
Possible Cause Action
1.No toner is available for print, or the
toner level is low. Shake the EP Toner Cartridge, replace
the cartridge if the problem persists.
2.The lenses within the Laser/Scanning
Assembly may be contaminated, blocking
(or diffusing) the laser light. Replace the Laser/Scanning Assembly.
Table 7-18Vertical White Streaks 
7-40 Troubleshooting