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HP LaserJet 4000, 4050, and 4100 Series Printers - Troubleshooting Fuser Print Quality Defects

Document number: BPL11829

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Special instructions

If the print quality defect can be isolated to an image repeat, using the following sections, replacing the fuser will not correct the issue. Refer to the troubleshooting steps in the "Image repeats" section.

If the problem can be isolated to fuser film wear, using the following sections, replacing the fuser will correct the issue. Refer to the troubleshooting steps in the "Thin vertical black line(s)" section.

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Instructions

Refer to the following sections to identify and troubleshoot fuser-related defects.

Perform a half self-test to determine where the defect occurs

Use the following directions to perform the half self-test.

  1. Open all paper cassette trays.

  2. Place a single sheet of letter-sized paper in Tray 1.

  3. From the Control Panel, select and print the PCL Configuration page.

    1. Press MENU until INFORMATION MENU appears in the printer display.

    2. Press ITEM until PRINT CONFIGURATION displays.

    3. Press SELECT to print the configuration page.

  4. Watch the trailing end of the page in Tray 1 as it advances into the printer. When the trailing end of the page is about to disappear into the printer, open the top cover to stop the print process.

  5. Remove the print cartridge and examine the partially printed page. If the print defect does not appear on the page, the defect is most likely occurring as paper passes through the fuser. If the defect does appear on the page, it is most likely occurring elsewhere and is not related to the fuser. Contact HP for further assistance.

Image repeats in 75 mm (2 15/16-inch) intervals down the page after fusing

NOTE: Replacing fuser will not correct issues related to this print quality defect.

Sometimes ghosting appears after printing envelopes or custom-size paper. This defect, referred to as hot offset, may occur on both the left and right edges of letter-size paper when alternating between letter size and envelope or custom-size pages, or when using letter-size paper after printing envelopes. The problem occurs because the edges of the fuser hot roller become hotter when printing on envelopes or custom-size paper, since they are not in contact with the media and are unable to dissipate heat into the media.

When a letter-size page is printed immediately after printing on envelopes or custom-sized paper, toner may be attracted to the hotter ends of the fuser hot roller and re-deposited down the page.

NOTE: This defect is less likely to occur with the HP LaserJet 4100. That machine has a variable zoned fuser that keeps the temperature across the hot roller more consistent.

Verify ghosting defect

  1. Print about 20 letter-sized pages and see if the defect goes away.

    NOTE: If the print quality improves, the defect is likely caused by toner that is attracted to the fuser’s hot roller, and then re-deposited on the page in 75 mm intervals.
  2. Select the default, SMALL PAPER SPEED = SLOW, in the printer’s control panel. This will slow down the print speed of envelopes and custom-size pages, and give the hot fuser roller time to recover between print jobs. If the defect continues to occur after printing at least twenty jobs after making this change, contact HP for further assistance.

    To set small paper speed to slow for HP LaserJet 4000 or 4050 printer

    1. On the control panel, press MENU until reaching CONFIGURATION MENU.

    2. Press ITEM until the display reads SMALL PAPER SPEED.

    3. Press the Plus (+) sign until the display reads SLOW.

    4. Press SELECT to save the change. An asterisk (*) should appear in the printer display, next to SLOW.

    To set small paper speed to slow for HP LaserJet 4100 printer

    1. On the control panel, press MENU until reaching PAPER HANDLING MENU.

    2. Press ITEM until the display reads SMALL PAPER SPEED.

    3. Press the Plus (+) sign until the display reads SLOW.

    4. Press SELECT to save the change. An asterisk (*) should appear in the printer display, next to SLOW.

      NOTE: A workaround for hot offset is to send five blank pages to the printer after printing envelopes or custom size pages. This gives the hot fuser roller some time to recover.

Thin vertical black line(s) on the page

A damaged print cartridge or fuser may cause thin vertical black lines to appear on the left, right, or both sides of the page (see Figure 1, call-out 1). Printing large quantities of envelopes or custom-size media may cause this defect. If the distance between the wear rings corresponds to the width of the envelopes or custom-size media being used, the media is prematurely wearing the hot roller film.

Figure 1: Thin vertical black line(s)

1 - Print quality defect

Printing test and cleaning pages

  1. Print a half self-test page.

  2. Print 20 letter-size pages if the print defect does not appear on the half self-test page.

  3. Perform two cycles of cleaning pages to see if the print defect remains.

    1. On the printer control panel, press MENU until PRINT QUALITY appears in the printer display.

    2. Press ITEM until CREATE CLEANING PAGE appears in the printer display.

    3. Press SELECT to print the cleaning page.

    4. Follow the instructions on the cleaning page to complete the process.

  4. Visually inspect the fuser. If the defect remains, check for wear rings on the film of the hot roller (see Figure 2, call-out 1).

  5. Replace fuser if there are visible wear rings in the hot roller film. If the print defect continues after replacing the fuser, contact HP for further assistance.

Figure 2: Fuser film wear

1 - Wear lines

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Removing and replacing the fuser (HP LaserJet 4000 and 4050)

1.0 - Removing and replacing the fuser
Figure 1.1a: Tray 2 dust cover Figure 1.1b: Optional duplexer
1.1.1. Turn the printer off and disconnect power.
1.1.2. Wait 30 minutes for the fuser to cool.
1.1.3. Turn the printer around to display its rear cover.
1.1.4. Remove the Tray 2 dust cover (see Figure 1.1a) or optional duplexer (see Figure 1.1b).
Figure 1.2: Rear output bin and extension
1.2.1. Unplug the power cord from the printer.
1.2.2. Open the rear output bin and pull out the extension.
1.2.3. Remove the rear output bin and extension. To do this, bend the middle down slightly, release tab 1, then release tab 2 (see Figure 1.2).
Figure 1.3: Left and right access cover
1.3.1. If a duplexer is installed, remove it. If a duplexer is not installed, remove the left and right duplex access covers from the rear of the printer by pulling each from the bottom.
1.3.1. Release the fuser by turning the fuser levers so that they point up.
Figure 1.4: Captive fuser screws
1.4.1. Loosen the two captive screws on the fuser assembly. 1.4.2. Pull the fuser assembly straight out of the printer. 1.4.3. Replace the rear output bin, left side first. 1.4.4. Plug the power cord into the printer. 1.4.5. Replace the Tray 2 dust cover or the optional duplexer.

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Reseating the fuser (HP LaserJet 4100)

1. 0 - Instructions for reseating the fuser
Figure 1.1: Remove the Tray 2 dust cover Figure 1.2: Remove the optional duplexer, if applicable
1.1. Turn the printer off and disconnect power.
1.2. Wait thirty minutes for the fuser to cool.
1.3. Turn the printer around to display its rear cover.
1.4. Remove the Tray 2 dust cover (see Figure 1.1) or optional duplexer (see Figure 1.2.)
Figure 1.3: Remove the rear output bin and extension
1.5. Unplug the power cord from the printer.
1.6. Open the rear output bin and pull out the extension.
1.7. Remove the rear output bin and extension. To do this, bend the middle down slightly, release tab 1, and then release tab 2 (see Figure 3).
Figure 1.4: Release the fuser
1.8. Release the fuser by turning the fuser levers so that they point up.
Figure 1.5: Remove the fuser
1.9. Pull the fuser out of the printer. To release the fuser from the printer, hold the back of the printer while pulling on the fuser as shown below. Do not pull on the black plastic flapper.
1.10. Lock the fuser in place by rotating the levers to the horizontal position. (The levers will lock only if the fuser is installed all the way.)
1.11. Replace the rear output bin, left side first.
1.12. Plug the power cord into the printer.
1.13. Replace the Tray 2 dust cover or the optional duplexer.

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Contact HP?

If the issue is unresolved, contact HP support and provide the following information:

Document number: BPL11829 was used for troubleshooting.

Problem description: (Provide the applicable questions and answers)

  • When did the issue(s) begin? Had something changed when this started occurring?

  • Does the print defect appear on the page during the half self-test? If so, describe the print defect.

  • Does the print defect appear after slowing down the print speed of envelopes and custom-size pages? If so, please describe the defect if not previously described.

  • Does the print defect appear after replacing the fuser? If so, please describe the defect if not previously described.

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