HP Laserjet Printer Repair

=HP Laserjet 4 and 5=

Cleaning up HP LJ 4, 4plus and 4Mplus printers (could be for LJ5 printer too)

Disassembly
place with a Bic pen spring) wrinkles and dirt and lifting it out snapping off the top rejuvinator fuser) pressing its tabs together remnants left * be careful of the tab on the bottom of the printer as it breaks off very easily * There are two internal tabs that need to be pressed down through a hole in the right side of the printer as well. squeezing together the two pivot points screws) out the two pivot points from their sockets and remove it
 * 1) open up the cover, take out the toner cartridge and put it in a dark
 * 1) take out the paper tray
 * 2) take off the right side skin (carefully press in two tabs)
 * 3) drop open the back cover (if you lose the spring, you can replace it
 * 1) Unscrew the 2 fuser screws and take out the fuser, check it for
 * 1) Take off the top of the printer:
 * 2) unscrew the two screws on the back of the printer FIRST!
 * 3) unscrew the one screw on top
 * 4) press in the two tabs and gently lift the top up and tilt it right
 * 5) unplug the user interface cable connecting the top to the printer
 * 6) Take off the rear exit transport by pressing in the two small tabs
 * 1) take the top panel off the exit transport by pressing the tabs and
 * 1) take out the top roller and treat the thicker rollers with rubber
 * 1) snap the top back on and save for later reinstallation
 * 2) Check the main drive gear in the back for broken teeth (it drives the
 * 1) Open up the memory door
 * 2) Take off the small black panel on the front of the printer by
 * 1) Open up all internal panels and metal lids to check for paper
 * 1) take off the left skin by pressing two tabs and lowering it to the
 * 1) take off the right front panel with the cartridge slot in it
 * 1) If broken, take off the single sheet feed tray
 * 2) detach the upper half of the tray from the lower by carefully
 * 1) take off the horizontal metal strip (with spring clip on left) (two
 * 1) take off the bottom piece by carefully bending the plastic to sneak
 * 1) release the spring (on the left side) from the top plastic piece

Cleaning
the rubber band to bring new rubber into the worn pick area
 * Clean off both feed rollers (large rubber wheels to pick paper)
 * For the bottom feed roller, press the clip to remove it and rotate
 * Blow out everything with compressed air and clean all surfaces

Reinstallation
two tabs printer
 * 1) Put rear exit transport back on.  Slide pins into slots and click in
 * don't forget to slide on the metal clip on the left side of the
 * 1) Put front single sheet feed plastic parts back on
 * 2) put horizontal metal strip with left side spring clip back on
 * 3) clip the two plastic pieces back together
 * 4) snap the small black front cover back on
 * 5) snap the front right panel (with cartridge slot) back on
 * 6) reinstall left panel. Put base tabs in and snap into place
 * 7) screw the memory door shut
 * 8) Put the top back on:
 * 9)  connect the user interface panel cable
 * 10)  snap the top down onto the printer
 * 11) add one screw in front-top and two screws in back
 * 12) Re-install fuser with two screws
 * 13) close the back cover
 * 14) re-install right side skin with tabs in bottom and snap into place
 * 15) put the toner cartridge back in and close the top toner door

Testing
4plus/4Mplus = $80?)
 * 1) - Put printer into offline mode (press online/offline button)
 * 2) - Press menu button until "test menu" appears
 * 3) - Press "next/index button" until "self test" appears
 * 4) - Press "Enter" to run the self test and print out an info page
 * 5) - Leave test page in output tray and put printer in store (LJ4 = $70,

Most common problems
jams)
 * rubber rollers on exit transport are shiny and smooth (z-fold paper
 * main drive gear running the fuser is broken or missing teeth
 * the front pick roller is dirty or smooth
 * the lower feed roller is dirty or smooth (rotate the rubber band)