HP Colour LaserJet Fading Fix

Step 1:

Unplug printer from the mains and detach your USB or Ethernet cable; take out the paper tray and all the cartridges (this makes the printer lighter and easier to handle).

Step 2:

Turn the printer around to look at its back. Remove the paper tray cover at the bottom and the paper holder tray at the top. Both just pull off.

Step 3:

Undo the screws on the back panel, including the one just below the USB and Ethernet ports. Put these screws into their own pile (later you will have another pile for all the screws you take out of the inner panel. Its a handy trick to help you ensure you put back all the screws you take out.

Step 4:

Pull the back panel off gently by holding it at the bottom and tilting it out and up.

Step 5:

Take a photo of the circuit board and wiring — you’ll want to refer to it when putting things back together, just to be sure you have done it all correctly!

Step 6:

Pull the right-hand side (as looking at printer from front) panel off, again it tilts upwards – note the way it slots and clips in (the middle plastic guide at the top of the panel). Remember that for when it comes time to slide it back on later. Gawk at the wonders of the printer. The reason for taking this panel off was to make it easier to pull out the wires from the back later; and because if you’re dismantling the printer, you might as well see how the whole thing looks naked.

Step 7:

Start taking off the cover of the left-hand side by first undoing the screw that is recessed in the handle/indentation at the bottom of the left-hand side’s panel. Then, pull the beige panel piece off, leaving the larger, grey panel piece for now.

Step 8:

Okay, now take off that grey panel piece by tilting it up and sliding it off (it has the same mechanism as the other side). Gawk again at the wonders of your printer. This is the high-voltage side. If you didn’t unplug your printer as I told you to, then you will be now convulsing on the floor and sporting a new hairdo.

Step 9:

Squint when really close to the circuit board on the back of your printer and you will see that each cable goes into a connector that is labelled something like “J106″. You will soon be taking these cables out and later you will want to put them back in – at the same place!

So, print out labels which you can attach to the cables. My label maker let me print out super-small letters and on two lines. You want small labels because the connectors are not that big. Here’s what I printed out (the ? or Enter or Return key is used to tell the label maker to go to the next line):

J106 J104 J103 J102 J101?

J108 J107 J105 J110

(My label maker wouldn’t let me print out any more than that in one go; so, being lazy, I didn’t bother labeling the very last cable connector).

Then, use scissors to cut each connector name out.

Step 10:

Now, pull each cable connector out, one at at time, and put the correct label onto it.

Note that the purple cables are attached to a plastic block (some black, some white) which is pushed into a plastic holder, like a small box – think of a baseball with purple strings sitting snugly in a glove.

Pull firmly on the purple cables (perhaps wiggling slightly side to side) near to where they go into the plastic block, this should remove the block from its plastic holder. Do not use tools, for fear of pulling out individual cables, or worse, pulling off the outter plastic box, instead of the block in which the purple cables are (as Piper, in the comments below, did).

Step 11:

Carefully detach the data cables, too, and unthread them from the plastic holder (you will soon be taking off the plastic holders). The data cables to the circuit board on the right side of the back panel also pull out quite easily and reveal a hidden screw! I didn’t bother labelling these as the data cables all stayed in the right order when disconnected.

Step 12:

Gently pull out all the cables from the two black cable trays. You’ll see that there are three layers of cables: thicker power cables in their own clips, and two bunches of thinner purple cables with some zip fasteners around them every so often. Its a bit of a (un-)weaving exercise…

Step 13:

Pull the empty trays to the side to unfasten them and then take them out completely – be sure no stray wire gets snagged by them!

Step 14:

Unscrew the back panel – no need to undo the two circuit boards themselves – they are both attached to a larger metal panel. Note that there is one screw that is in horizontally on the top-left (this is why you took off the side panel!). Note that your printer may not have the extra memory card inserted as I have in mine (see picture).

Step 15:

Pull out the back panel with the two circuit boards on it. Be sure that no cable is snagged, or left attached.

Step 16:

Ah-ha! There it is! That is the optical box we’ve been working so hard to find! Three more screws and we’ll have it…

Step 17:

Okay, you found the two screws holding the optical box at the top; but where is the third screw that I mentioned?

Tip: tip the printer so you look at the bottom of it, where the paper tray usually goes.

See them? Two shinny plates. They bend when you pinch them with your fingers. Now, on my printer there was a screw beneath just one of them. Feel lucky? Which one will you take off? Were you lucky? Or maybe your printer has a screw underneath both…

The screw holds the bottom part of the optical box. Take out the third (and maybe forth) screw.

Step 18:

Gently lift up the optical box and remove the pair of data cables that go to it. Again, I didn’t bother labeling these as they stayed in the same position/order and wouldn’t get muddled up when I reassembled everything.

Step 19:

Pull out the optical box and undo the screw that is in the middle of it. Be careful – there’s a spring in the box. Take off the cover and…

Step 20:

At last! There are the filthy mirrors that are the cause of this nightmare. If only HP has seen fit to seal this optical box then none of this would have been necessary…

Okay, that wasn’t really a step, it was just some soap-boxing. Here is the real step 20:

Clean the mirrors using dry cotton swabs!

Step 21:

Gawk at the wizardry of the optical box, its lasers and your nice shiny mirrors. Play with the flaps that cover the laser openings — don’t loose that spring which is between the flap mechanism that covers the laser diodes and the optical box.

Step 22:

Reverse everything and put it all back together again. Simple. Ha!

Be sure that you seat the optical box back exactly right – ie. don’t leave it loose!

Putting those cables back in the plastic trays is the most challenging. Just remember to put the two bundles of purple wires in first (the largest bunch, which splits at the right side to go up and down, should be at the very back of the tray; the other bunch on top of it; and finally the power cables should fit into their special holders at the very edge of the trays).
Note carefully how to feed the data cable around the tray at the left side.

Double check that you haven’t pinched any cables around corners, etc.

Did you use up all the screws? I sure hope so, otherwise you’ll have to undo everything to find out where you missed them…

Step 23:

Underside of the printer; note the black grill on top left - that's the air intake for the fan.

(optional) On the first anniversary of this page, and my second go at cleaning the mirrors (yup, they got dirty enough in the one year to warrant going through this lot all again), I decided to slap on a homemade air filter to the fan intake.

Make sure you don’t have the paper tray installed; and then tip the machine onto its front, so that you are looking at the underside of it. You’ll see a black grill or grate.

Vaccuum cleaner bag cut to fit over the grill, so it acts as an air filter.

Get yourself a vacuum cleaner bag and cut it to fit over that grate. Use some cellotape to stick it in place. You may very well have to do as I did and cut little slits in the bag so it fits over the silly extruding bits of plastic. If I haven’t already said it, I’ll say it now: this printer is over engineered!

Now tip the printer back to its normal position and install the paper tray.

Step 24:

Re-load the ink cartridges; paper and plug everything back in.

You must now recalibrate the printer (this aligns all the lasers so the colours match up and don’t give you a blurry photo print).

You can navigate your way through the printer’s front panel menu to force a calibration:

• Press the check mark key (screen shows “Main Menu – Reports”)
• Press right arrow key (“Main Menu – System Setup” shown)
• Press the check mark key (“System Setup – Language” is now shown)
• Press the right arrow key twice (“System Setup – Print Quality” is shown)
• Press the check mark key twice (“Calibrate Color – Calibrate Now”)
• Press the check mark key (“Press [v] to calibrate now”)
• Press the check mark key (calibration begins)

Alternatively, you can use the printer’s built-in web server over the Ethernet port to force an immediate recalibration (sorry, don’t know what you do via USB).

Step 25:

(optional) Unconnected Connectors and An Interesting Button…
While you had the covers off and the circuit boards exposed, did you notice that there are a few unconnected connectors and a “test” button?

One connector is “IOT” and the other is “MCPU Writer”.

After I reassembled and plugged everything in, I pressed the “test” button. I got a boring printout of colour lines.

Step 26:

Please leave a comment below to say if this page helped you; or, if any steps were unclear. Happy colour printing!