Tools of the Trade 4500/4550 & 4600/5500 Internal Diagnostics15 Jun, 2003 By: Stephanie Hinz imageSource
Tools of the Trade 4500/4550 & 4600/5500 Internal Diagnostics
Imagine a doctor
performing surgery without a scalpel, or a student without books. Picture a
plumber trying to unclog a tough drain without… well, you get the idea. Just
like each of these professions, a printer technician cannot complete the task at
hand without the proper tools. Internal diagnostic tools are often the first
line of defense for troubleshooting printers. These tools act as a starting
point or guide to diagnosing and correcting problem printers in a timely
fashion. Where once it may have taken hours to diagnose a problem, internal
diagnostic tools make troubleshooting easier and allow technicians to narrow
down the field to specific areas of concern.
Despite its popularity, the HP Color LaserJet 4500/4500 can be a challenge to
work on. When diagnosing a problem, it is beneficial for technicians to
familiarize themselves with the machine's internal diagnostic tools. Using these
tools as a first line of defense will often lead to faster and easier repairs.
should first check the formatter diagnostics which test the functionality of the
NVRAM (non-violate random access memory), the Firmware ROM (Read-only memory),
and any optional memory DIMMs (Dual-in line memory modules). To enter this mode,
hold down the left side of the "item" key while starting the machine.
These tests can be used to diagnose any number of internal communication errors.
The most common relate to the on-board memory or firmware. The options include:
ROM CRC-This option verifies the operation of the printer's firmware (often
defined as the machine's operating instructions) and is for the 4500 series
only. This is perhaps the most valuable option in the menu because the ROM or
Firmware cannot be removed from the machine.
> DRAM (Dynamic Random Access Memory)-Checks for proper functionality of the
on-board RAM (Random Access Memory) and optional memory DIMMs.
> SRAM 1 (Static Random Access Memory)-Checks the memory inside the ASIC.
> SRAM 2-Tests the memory embedded in the formatter.
> NVRAM-Use this test cautiously! HP recommends this test only be run if the
printer is having a problem holding these settings (page counts, serial number,
etc.). If this test is initialized, come prepared with a good book because it
can take up to an hour to execute. Beware, canceling the test by turning off the
printer on the 4500 may damage the NVRAM. Therefore, do not interrupt the test.
Job Cancel will terminate the test on the 4550 but do not turn the printer off
to stop the test on either model.
diagnostics tools are useful in isolating mechanical assemblies as opposed to
logic components. The menu is accessed just like formatter diagnostics; holding
down the left side of the item key until "engine diagnostics" is
displayed. Pressing job cancel will cancel each test on the 4550 series only.
The options include:
Paper Path Test-This option will engage the fusing, pickup and drum drive motor.
The paper feed solenoid can also be manually activated to engage the pickup
rollers. The ITB (Intermediate Transfer Belt) clutch fires and completes a full
rotation. If the clutch is operating correctly, the ITB cam assembly will
engage. One of the most common failures on the 4500/4550 is directly related to
the ITB cams. In some cases, only one side of the cam assembly will lift
properly causing the color image not to transfer accurately. In other cases, the
cam assembly fails to engage at all due to a defective ITB clutch.
> Developer Test-Another common problem is associated with noises created by
problems with and around the carousel assembly. This test rotates the carousel
assembly and developer sleeve. The best way to use this tool is to bypass the
ITB door switches to observe the carousel in action. To access the ITB drawer
switches, remove the left side cover and the ITB drawer. Defeat SW 1 and SW 4.
The cartridge may also be removed during this test. The best example to
illustrate the convenience of this test is the dreaded 54.2 carousel jam error.
If the carousel assembly appears to be free of any debris, this test can help
locate the source of the problem.
> Drum Drive Test-This option locates problems related to the drum drive
motor assembly. The test engages the ITB clutch, transfer roller clutch and the
cleaning roller clutch. The cleaning roller clutch will engage for a few seconds
then disengage then engage again until the drum drive test is terminated.
> Path Sensor and Door Sensor Test-These are two separate tests but work
almost identical. The ITB needs to be installed and both trays removed for this
option to work. In this diagnostic mode, the display will show a series of
letters that correspond with a particular sensor. Each letter will be assigned a
value of either 0 or 1. When a sensor flag is toggled or a paper size switch is
pressed, the value should change. If the value does not change, the sensor or
switch has failed. The same procedure applies for the door sensor test. The
service manual is extremely helpful when using this test because it defines each
sensor according to the assigned letter.
While the new 4600/5500 color lasers are more "tech" friendly overall,
problems will undoubtedly occur as the products age and use increases. The
diagnostic menu on the 4600/5500 is easier to navigate and run than its
predecessor, with a couple valuable new tools. The diagnostic test mode can be
accessed through the regular menu and the options include:
1. Print Event Log-The event log displays the last 50 errors generated by the
machine beginning with the most recent. This is a standard option available on
most HP Color and Monochrome LaserJets.
2. Show Event Log-If the machine is unable to print, the event log may be
accessed and viewed with this option.
3. PQ Troubleshooting-This diagnostic tool is new to the HP Color LaserJet
family. This option will produce four print quality test pages (one of each
color), each containing a defect grid.
4. Disable Cartridge Check-This option is very beneficial and fun to play with!
Once selected, the print cartridges may be removed and swapped to troubleshoot
image quality or noise problems. All messages related to supply errors are
bypassed during this mode and test pages may be initialized through the control
panel. If you are experiencing a problem with a specific color, this test can
help isolate between the cartridge and its slot.
5. Paper Path Test-Unlike the 4500/4550, this option will not allow the paper
feed solenoids to be manually activated or other components to be removed to
observe gear motion. Yet, like most HP printers with this option, the paper path
test can determine the cause of most paper jams by selecting which input tray to
use, then choosing the number of desired copies. If, for example, a 4600 is
jamming paper in the middle of the paper path and the printer is configured with
an additional 500-sheet tray, this test will help determine which tray is the
source of the problem.
6. Sensor Test-This test operates exactly like the 4500/4550. Some of the sensor
flags are difficult to toggle, but this option is a helpful troubleshooting
tool. Once this mode is accessed, the panel will display a row of letters (A-H),
which corresponds to a particular sensor. Each sensor will have an assigned
value (0 or 1) and when the flag is toggled the value should change if the
sensor is working properly. Once again the service manual is helpful to properly
diagnose sensor related problems.
7. Component Test-This is another valuable and fun tool. This option checks the
functionality of the following components: transfer motors, ETB (Electro-static
transfer belt), cartridge motors, all four laser scanners, fuser motor,
disengaging motor, (also called the alienation motor), and finally tray 1 &
2 paper feed solenoids. Unless you are testing the ETB motor, the front cover
switch can be manually activated to run this test without the cover or the ETB
The transfer test engages all transfer related components. This includes the
cartridge motors, the ETB and all four cartridges, if installed.
> The Belt test exercises the ETB motor assembly. The print cartridges must
be removed to avoid damaging the ETB assembly and the ETB connector must be
fully engaged. If not, the machine will display a 59.9 motor start up error.
> The next test can rotate all four cartridges simultaneously or one at a
time. To initialize all motors at once, all four print cartridges must be
removed to avoid contact with the ETB. To isolate one of the cartridge motors,
remove the corresponding cartridge. HP recommends initializing the test with all
print cartridges installed before proceeding.
> The next option is another new diagnostic tool. Since four separate laser
scanners are used to write the image, this option will spin each scanner motor
8. Fuser motor-This
test rotates the fuser motor and gears.
9. Alienation Motor -Also called the developing disengaging motor, this option
engages the disengaging plate, which rocks the developing cylinders against the
photosensitive drum during printing and away during the cleaning. If, for
example, the developing cylinders were to remain engaged during a monochrome
only print, most likely the page will be streaked with color toner. The last
item in the component test is the Tray1/Tray 2 solenoid test that activates both
10. Print Stop Test - Finally, the diagnostic test we have all been waiting for.
You can actually program the printer to stop paper in the path to troubleshoot
image defects. The test can be programmed from 0 to 60,000 mS (milliseconds),
which converts to 0 to 60 seconds. This test allows the service technician to
consistently stop a page in the same place.
For many, the
4500/4550 is an intimidating machine to service, but knowing how to access and
use the printer's diagnostic tools will save time in addition to allowing you to
familiarize yourself with the printer. Hopefully, the diagnostic menu on the
4600/5500 is an option HP will expand further and include with future color and
monochrome models. As you can see, these diagnostic tests are just as important
to a service technician as the law is to a lawyer or the scalpel is to a
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Hinz provides printer training and technical training for PARTS NOW!, a major
printer parts wholesaler for HP, Canon, Lexmark and Okidata. To contact PARTS
NOW!, call 800.886.6688 or visit www.partsnowinc.com.