HP Laserjet 5 Service Manual

							Distorted Image or BD Failure
·Make certain the printer is not facing the sunlight.
·The paper may not meet HP’s paper specifications. Select different paper.
·Clean the Laser/Scanner Assembly by blowing compressed air in the slot on the
bottom of the assembly.
·Make sure the two Laser/Scanner connectors are firmly seated.
·Replace the Laser/Scanner unit.
·
Replace the DC Controller.
7-20 Troubleshooting 
						

							Troubleshooting Checks
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, so this test is
useful for isolating printer problems. The engine test prints a full page of vertical
lines down the entire printable area and is also useful for checking and adjusting
registration.
Engine Test Button Location
The engine test print button is located on the DC Controller PCA. It is accessible
through a hole at the front of the printer. (See Figure 7-4.)
Printing an Engine Test
The engine test button is accessiblewithout removing the covers. To print an
engine test, use a long,non-metallicobject (such as a pen or pencil) to press the
engine test button. A single test page is printed. (See Figure 7-4.)
Engine Test
Figure 7-4
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Troubleshooting
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							Half-Self Test Functional Check
The electrophotographic process can be subdivided into the following stages:
·Cleaning (removing excess toner from drum surface)
·Conditioning (placing a uniform electrical charge on drum)
·Writing (laser strikes surface of drum to create latent image)
·Development (formation of the toner image on drum)
·Transfer (charge to transfer the image to paper)
·Fusing (heat and pressure to produce a permanent image)
The purpose of the Half-Self Test Check is to determine which process is
malfunctioning. Perform the test as follows:
1Initiate a self test.
2Open the Printer Door after the paper advances half-way through the printer (about
8 seconds after the Motor begins rotation). The leading edge of the paper should
have advanced past the toner cartridge.
3Remove the toner cartridge.
4Open the toner cartridge’s drum shield to view the drum’s surface.
If adark and distinct toner image is presenton the drum’s surface, assume that the
first four functions of the electrophotographic process are functioning (cleaning,
conditioning, writing and developing - see Chapter 5.)  Troubleshoot the failure as a
transfer or fusing problem.
IfNO image is presenton the photosensitive drum, perform the following functional
checks:
1Make sure you have removed the entire length of the sealing tape from the toner
cartridge before you installed the cartridge.
2Drum Rotation Functional Check.
3High Voltage Power Supply Check.
7-22 Troubleshooting 
						

							Drum Rotation Functional Check
The photosensitive drum, located in the toner cartridge, must rotate for the print
process to work. The photosensitive drum receives its drive from the Main Drive
assembly. To verify whether the drum is rotating:
1Open the Printer Door.
2Remove the toner cartridge.
3Mark the cartridge’s drive gear with a felt-tipped marker. Note the position of the
mark.
4Install the toner cartridge and close the Printer Door. The start-up sequence should
rotate the drum enough to move the mark.
5Open the printer and inspect the gear that was marked in step 3. Verify that the mark
moved.
If the mark did not move, inspect the Main Drive assembly to ensure that it is
meshing with the toner cartridge gears. If the drive gears appear functional, and the
drum does not move, replace the toner cartridge.
NoteThis test is especially important if refilled toner cartridges have been used.
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							High-Voltage Power Supply Check
The High-Voltage Power Supply PCA provides the necessary voltages for the
electrophotographic processes. A method for verifying the high-voltage system is
given in the table below.
Toner Cartridge High Voltage Connection Points (1 of 2)
·Charging (1)
·Drum Ground (2)
·Developing Roller (3)
Checks Action
Toner Cartridge Connection Points Visually inspect the three connection points on the
underside, right end of the toner cartridge. If they
are dirty or corroded, clean the connections.Use
alcohol only. If damaged, replace the toner
cartridge. (See Figure 7-5 below.)
High Voltage Connector Assembly This assembly uses spring-loaded pins to contact
the toner cartridge. (See Figure 7-6 on the following
page.) Verify that the pins are not dirty or corroded
and that the spring-loading action is functional. If the
pins are dirty, clean using alcohol only; if damaged,
replace the High Voltage Connector Assembly.
Table 7-5High-Voltage Power Supply Check
Figure 7-5
7-24 Troubleshooting 
						

							Toner Cartridge High Voltage Connection Points (2 of 2)
·Charging (1)
·Drum Ground (2)
·Developing Roller (3)
Figure 7-6
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Troubleshooting
Troubleshooting 7-25 
						

							Paper Curl
Paper curl is inherent to the laser printing processes, and occurs when paper is
subjected to heat. Paper curl tends to relax as the paper cools while resting on a flat
surface. The specification for maximum paper curl when the paper is lying flat
before print is 5 mm (0.2 inches).
Although paper curl cannot be totally eliminated, some steps can be taken to lessen
its impact, as suggested in the following table.
Possible Cause Recommended Action
Paper Path Try using the front output slot to shorten and straighten the paper
path.
Paper Surface The recommended printing surface of the page is usually marked
on the end of a ream of paper by a small arrow and the phrase
“print this side first.” If the incorrect side was face up, turn the
paper over. Load paper into the Paper Input Bin with the
recommended printing surface facing the front of the printer.
Paper Storing and Handling Over time, paper assumes the characteristics of its storage
environment. (In a humid environment, paper absorbs moisture. In a
dry environment, paper loses moisture.) Paper with higher
moisture contents will tend to curl more. Evaluate the storage
conditions of the paper.
Paper Type All paper is manufactured differently (texture, moisture content,
drying processes, composition, etc.). Change the type of paper
being used and re-evaluate the paper if curl results.
Table 7-6Paper Curl Troubleshooting
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							Troubleshooting Tools
Paper Path Check
If paper is not being picked up or is not moving through the paper path, you may
want to observe all of the paper motion activities. Overriding PS204 (5L) or SW101
(6L) allows you to observe:
·Motor rotation
·Solenoid action
·Kick plate motion
·Paper Pickup Roller motion
·Drive Roller, Transfer Roller, Fuser Roller and Gear, and Delivery Roller Motion.
To override PS204 and SW101
1Remove the Printer Covers (Figures 6-2, 6-3, and 6-4).
2For HP LaserJet 5LPrinter only:Press the Door Open flag down (Figure 7-7,
callout 1) and lift the EP Cartridge flag (Figure 7-7, callout 2). These flags are
located on top of the printer chassis to the left of the Laser/Scanner assembly.
For both HP LaserJet 5L and 6L Printers:Press SW101 (Figure 7-7, callout 3).
Overriding PS204 and SW101
3While holding the flags up, perform either an Engine Test or a Self Test to observe
paper motion. (See procedures earlier in this chapter.)
Figure 7-7
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Troubleshooting
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							Repetitive Image Defect Ruler
Repetitive Image Defect Ruler
Figure 7-8
7-28 Troubleshooting 
						

							Main Wiring Diagram
Figure 7-9Main Wiring Diagram
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Troubleshooting
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