Todd in Ohio

asked Aug 8, 2011 at 10:18am
Hp HP Color LaserJet 2840

HP Color Laserjet 2840 spitting out blanks

Hello all.

I have an HP color laserjet 2840 that worked well until it needed a yellow cartridge. I purchased what I THOUGHT was an HP toner, but when it came in the mail discovered it was a knock-off. I installed it and it hasn't printed since. It kept saying I needed to reinstall the cartridges and that the other cartridges were empty.

I looked online and used the instructions to flash the RAM, but that didn't help (I had previously installed the max amount of RAM for this printer).

I purchased all NEW HP branded toner cartridges, but that didn't work. It said everything was good, but only spit out blank pages when printing/copying.

Today I installed a new toner drum ($$) hoping for this to fix it. It went through the calibration process fine. However, it still prints out blank pages. BTW, the scanner light works and moves under the flatbed just fine so that doesn't seem to be the problem.

I've invested a lot of money into this behemoth (purchase plus all new toners and drum) and would like to get it to work before chucking it out my window.

Any advice would be appreciated.

Todd in Ohio
Well, I finally decided to take on the task of taking the printer apart as you instructed, and very soon I realized that I needed a diagram or two to know which covers to remove were which and how to remove them. It's not self-evident. Is there a link to appropriate diagrams somewhere?
by DougWilson on Nov 24, 2012 at 8:01pm Add comment
I'm going to have you do an engine test. To do so, lower the MF tray at the front of the printer. With your left hand, reach up on the top left of where the tray is and feel around for a dangling plastic lever. When you find it, push up on it. That will initiate a lined engine test print. It bypasses everything else and just tests the engine.
by moe on Aug 8, 2011 at 10:37am Add comment
I've done the alignment...and cleaned the relay. The engine test failed. Completely blank page. What's next? - 1faron
I did as you requested (three times to make sure). I spit out pages with horizontal lines on the far RIGHT of the page evenly spaced and about 1/8 inch apart all the way down the right side. They varied from 1/4 to 1/2 inch in length. The right border almost abutted the right side of the sheet of paper and the left faded.


PS I'm off to work in a bit so won't be able to test, although I'll be able to read your post on my phone. Thanks again.
by Todd in Ohio on Aug 8, 2011 at 10:44am Add comment
i'm guessing that the reman'd cartridge knocked the carosel out of alignment. i'm dealing with a 2550 with this exact issue right now. good write up from moe at this thread (read moe's instructions from 2/5/11):
by chris on Aug 8, 2011 at 12:56pm Add comment
Thanks for that. I would have sent him there on the first post, but he said the whole page was blank. That's why I told him to initiate an engine test page. Good luck with the 2550. It's real easy after you've done the first one. The only times I'll ever take a 2840 apart is when the carousel brake solenoid stick. What a pain that is. - moe
Thank you to Moe via Chris. I'm still at work, but will try it when I get home. Update to follow.
by Todd in Ohio on Aug 8, 2011 at 4:08pm Add comment

After reading the post about alignment issues I took a look at my printer and noticed it was way off. I must've really man-handled those cheap toner cartridges.

Turns out in my printer the solenoid is on the right not the left.

It took me about half an hour to complete. Now that I've done it, doing it again would probably take 10 minutes.

It now prints perfectly.

Thanks ever so much. This printer has been sitting in my closet for a year as a symbol of my frustration and now it's fixed. Wow

by Todd in Ohio on Aug 8, 2011 at 7:54pm Add comment
Where did it say the solenoid was on the left? - moe
Where did it say the solenoid was on the left? - moe
Oops. I read this last evening inbetween surgical cases at the hospital. Must've had a dyslexic moment while reading it. Todd
by unknown on Aug 9, 2011 at 5:11am Add comment
Just wanted to say thanks Moe. I dont know which post I read about this but helped me to easily realign the gears without any tear down. 3rd party magenta cart was the problem.
by nivek on Aug 9, 2011 at 9:11am Add comment
The page is not printing. It only prints on the right side 1/8th of the page. I have little splotches of red toner at the top and there is a red toner line with a loud noise every time the page prints. Sounds like this thing is ready for the trash. It's 5 almost 6 years old.
by gigi169 on Oct 26, 2012 at 8:50pm Add comment
All you need is in here.......... - healthup
OMG, worst camera work I've ever seen. I've done the procedure numerous times and had no idea what he was talking about. Probably the only thing you might get out of the video is how to unlock the carousel and even that is kind of sketchy.
Once you unlock it and remove the toners, ignore all the rest of the crap. Pick any color and align the cartridge slot on the left side like you would have it to remove the cartridge. Then pull out on the gear towards you on the right and drop it so the right slot is lined up as well. You can get it aligned pretty close by just eyeballing it visually. I've never seen the left side go out of alignment, just the right, so this method has worked for me everytime.
Use this video to unlock the carousel
This video describes the procedure I quoted.
by moe on Oct 27, 2012 at 2:03pm Add comment
Moe, my precise problem is very similar, but the printer will print black just fine, e.g. letters, but anytime there is color, it not only doesn't print black, it will only print yellow portions. Or a blank.

BUT when I installed a new Windows 7 print driver downloaded from HP, it printed a configuration page with all colors (though no black -- not sure if that page had black on it).

So then I printed a Supplies Status report, and once again, got only some pale yellow. The supplies status on the device Ready indicator show full supplies, which it should since I just replaced everything, including the drum, all HP sourced. But like Todd in Ohio, I had previously ordered some refurbished replacements for low cost, and that's when the trouble started.

Is the fix the same, or is something else screwy?
by DougWilson on Oct 28, 2012 at 1:25pm Add comment
Your issue is the carousel solenoid brake is sticking. Similar to paper pickup assemblies the carousel has a solenoid that stops the carousel in the correct position for each color. There is a "L" arm which when no power to the solenoid sits in a cutout of the carousel right side for a color and when you send a print job the solenoid is activated and the "L" arm moves from the cutout, power is turned off to the solenoid and it presses against the ledge until it reaches the next cutout which is the position for the next color to be transfered to the drum unit. To stop the loud noise they used a dampening pad which over time wears out and all that is left is the glue that held it in place. So now when the solenoid is activated the "L" arm is attracted to the center of the solenoid and when power is turned off the glue makes it stick so it is unable to stop the carousel at the correct position and no color is transferred to the drum unit. Pain to get to. You have to remove the left and right side covers, the two top front covers and the top cover. You then have to remove the back right cover over the scanner holder and then remove the formatter. You then have to remove the motor at the top which drives the carousel and then remove the metal cage that covers the solenoid. Most of the solenoids have 2 yellow wires that run to a connection on the dc controller. You remove the connection and then remove the solenoid held by one screw and remove it from the the printer part way since you want to leave the cable near the top so you can draw it back down when you are finished. You remove the spring on the solenoid, remove the "L" arm and clean off the ledge of the solenoid where the glue is present and also clean off the "L" arm. You that have to put a replacement pad on the ledge. If you do not put a new pad down the arm becomes magnetized which makes the situation worse. They sell the material you need at this site.

Put everything back together and it will work just fine. Just about everyone I have seen where this happens it is just a portion of yellow that appears on the page. The other times you are missing one of the other colors.
by dmzcompute on Oct 28, 2012 at 4:24pm Add comment
Thank you! But please give me the idiot treatment here:

1. What is the specific nomenclature for the replacement pad I need?

2. Do you have any photos or video of the parts and innards of the machine, especially the solenoid, or know where I can get a look at what I'll be looking for? It may be obvious once I get in there, but a picture is worth a thousand words sometimes.

Thanks again, looking forward to further advice.

by DougWilson on Oct 28, 2012 at 5:03pm Add comment
Just a felt pad. You will see what is left of the old pad. Sometimes you can use a thin furniture pad that you put on the bottom of the legs so the floor is not scratched.
by dmzcompute on Oct 28, 2012 at 5:20pm Add comment
OK. Thanks again.
by DougWilson on Oct 28, 2012 at 5:33pm Add comment
Is anyone still able to help on this thread?

I just bought a used HP 2840 and when I try to print in color I get a blank page. If I do an engine test, only the black lines print out, no colored lines. I don't know what the engine test means. I checked the alignment and it is correct. So is this a sticky solenoid problem?

(If so, I tried to take off the cover to get to the solenoid to have a look but I can't get all of them do people manage to do it in half an hour?!! Please help!)
by unknown on Sep 19, 2014 at 1:10am Add comment
The ultimate fix earlier prescribed, the little pad, is very cheap, but I was never able to get a diagram, and when I approached the task without one it seemed very difficult to navigate and easy to screw up, so I gave up. By now this equipment is so obsolete, and the ink so expensive, that I found the little Epson printer I got as a temporary backup was all I really needed. But for a lot of copying and printing perhaps one of the newer HP models will meet your need. I hope you didn't pay too much for your used one.

Doug Wilson

- DougWilson
Nevermind, it was indeed solenoid sticking.
by unknown on Sep 19, 2014 at 5:00am Add comment
I use a laproscopic procedure I developed. Simply put, you remove the right side panel. You need to pop off the plate covering the right hinge and pop the top of the arms out of their holders. Then remove the metal formatter box. Loosen the motor and let it dangle. You now have access to the solenoid through a hole adjacent to it. Using a pocket knife, scrape off the goo. Then with a tweezers insert the new pad and push down on the plate to secure it. Whole job takes less than 10 minutes once you've done a few.
by moe on Sep 19, 2014 at 7:31am Add comment
Hi Moe,

I am having the same problems on my Laserjet 2840 and would like to try to laproscopic procedure you referred to above. I have popped off the plate covering the hinge but am not sure how to remove the right side panel. Can you explain in more detail? Your help is greatly appreciated.

by newtofoop on Jan 12, 2015 at 6:07pm Add comment
It's been awhile since I've done one and I'm old and don't remember detail anymore. I believe there is one screw at the bottom of the panel in the recessed hand hold area and then you use your fingertips to pop off the front of the panel. Of course, it's a lot easier when you're looking at it.
by moe on Jan 13, 2015 at 11:39pm Add comment

Moe- You are the man!

A little more detail for anyone who googles this: The right side cover has 2 screws at the bottom near the hand hold, take thos out and pull out on the bottom of it. The right hinge cover comes off- open up the lid and there are 2 places to unlock tabs which are attached to it, slip a screwdriver under and pull up slightly. After that is off the vertical right side panel can come off. Formatter box has 4 screws and several cables to undo. Then you can see the motor for the drum, 2 screws hold it on. After you take it off you can see, through the hole where it fits, the solenoid, arm and stop . Look closely at the space between the stop and arm and you should see remains of the foam bumper pad. Clean that all off by scraping, tweezers, and alcohol, and put in a new one. I used a piece of camera light seal foam but other things would work as well, just not too thick or the solenoid arm can't close enough.

by scottct on Jan 11, 2016 at 2:55pm Add comment

I am about as far from technical as they come. I was HIGHLY MOTIVATED to make my ancient HP Laserjet 2840 print something more than just yellow, though! I needed a fax activity report proving I sent a fax when I said I did ... but fax reports printed a completely white sheet. I watched YouTube videos with no words (but really janky background music) and it was just too hard to take off the entire top of this monstrosity to get to it from the topside. I read Moe's laparoscopic approach and added Scott's detail along with 15 Google search windows open and the official repair guide pdf from HP. IT WORKED! I wanted to cry when I had to look through that tiny hole to clean all the junk off the solenoid arm and I dropped more than a few tiny pieces of electrical tape in places they should never go. What took you 30 minutes, took me 4-1/2 hours ... but I was victorious. THANK YOU!

PS - But why is there always one extra screw?
by Charlene A on Dec 3, 2017 at 8:48pm Add comment

I made this fix today at my printer. Im really glad to have fond this hint.
Many thanks

by ChristophP on Jan 16, 2021 at 9:27am Add comment

I cleaned the ledge & "L" arm and replaced the old pad with one layer of vinyl electrician's tape. Turns out I needed TWO layers of tape to separate the arm from the solenoid because residual magnetism from the solenoid wasn't releasing the "L" arm and the printer continued to send out blank pages. To test, hold the "L" arm against the pad and see if you can slide a piece of paper between the arm and solenoid core. That worked for me. I like my 2840 and it's worth it to fix.

by Bugless on Mar 9, 2021 at 11:30am Add comment