HP aio 2840 prints blank or Yellow, fax and copying is in full color

[VoxB]

The printer prints blank or yellow. Fax and copying is without any issue and in full color. What can be the reasen for this malfunction between fax/copying and printing.

[SHThompson · Accepted solution]

I'm trying to think of the proper name for it but this item that has failed is the solenoid of that latches the carousel into position.

This solenoid holds the carousel still while you're printing any given color, and then releases so the carousel can be rotated the quarter turn it takes to get to the next color.

What happens is that when the carousel does not latch the toner cartridge drifts out of position and none of the toner transfers to the intermediate transfer belt. Sometimes you get yellow what is the first color of the 4 it lays down for an image.

What is actually happening is the foam rubber piece that is in between the solenoid arm and the magnetic coil deteriorates and become sticky and the arm sticks to it instead of latching the carousel into position.

To fix it you need to disassemble the machine to where you can remove the solenoid, then remove the arm from the solenoid it's pretty simple when you look at it. Then clean off the tarry residue and replace it with a very thin felt pad, you can get them at a dollar store, if you buy the higher quality pads they are way too thick and the solenoid won't work. You need to have something in between the metal arm and the metal center of the solenoid or the residual magnetism that has developed in the metal will cause the two pieces to stick together.

You can find the service manual for this machine at: feedroller.com

If my post resolves your issue please click the accepted as solution button under it. To thank a technician for a post click the thumbs up button under the post. You can even click both buttons. <g>

[SHThompson]

Can't explain why copying will work and printing won't except that it is coincidental and eventually your problem will show up when copying.

[VoxB]

I'll try your proposed solution. What I don't understand, what is the different between printing as a printer and printing as a copier? Because the printer works fine when he works as a copier or as a fax.

[SHThompson]

There is no difference as far as the printing is concerned so it is a mystery that it is working as a copier but not a printer.

Now are you making color copies or black and white? When you make a black and white copy the carousel doesn't have to move between the colors.

[SHThompson]

By the way that latch is essentially the same in the Color LaserJet 2500, the 2550 and in your machine.

I mention that because I found a video on YouTube where someone is demonstrating working with the latch and the 2500.

SHT

[VoxB]

I sent a technicien at place and indeed, only black printing is functioning. The customer wants a new printer, so case closed.

[Toolman1184]

I have the same problem and my printer is copying in color and black and white as well.  What is the serviceable part called in the service manual?

[SHThompson]

I think it's the rotary drive assembly.

You can find YouTube videos for the Color LaserJet 2500 showing the part. The 2500 uses the same print engine as the 2840.

[MiragePilot]

My HP 2840 had the same problem (printing only in yellow and then eventually not recognizing any of the cartridges and then not rotating the carosoul correctly).

I carried out the repair as described above, but after I reassembled the machine and turned it on, it did not complete the initialization (you could hear the carosoul was not turning like it should). It eventually threw up a "Incorrect Yellow" error message.

If the replacement pad on the solenoid is too thick, would this lead to the error/failure (after the "repair") I described above?

Thanks for the help,

Peter