M451, printers

PROBLEM; “Cleaning followed by MisPrint” issue on the HP pro 400 – M451 and CP2025 Series Color Printers

This is a very common problem with both the Color Pro 400 series and the CP 2025 series printers.  When sending a print job it will begin to print. Then you will see that the printer has gone into “cleaning mode” followed by “Misprint”. Then it will ask the user to press “OK”. Then if you select ok, it will try to re-print the job but “Cleaning mode” will begin and the whole process will start all over again. I can see the frustration in your eyes and I’m not even there. If you pull out the paper tray carefully you will see that the paper has fed in just a bit and is laying inside. Not to worry there are a few solutions besides replacing the machine that seem to help.

The easiest way to get yourself printing again is to slow down the machine. I will explain the reason why this works later in my article. Go into the paper handling menu and set Tray 2 paper type to “Heavy – 111-130g”.
The reason why I don’t like this method is because it slows down your printer. The M451dn prints Letter size color pages at 21 pages per minute (ppm). If you are doing a large print job you will notice a drop in speed.

For your information, Hewlett Packard will replace the machine on exchange if it is still on Warranty.  If it is off of warranty you will have to pay to exchange it or you can try the fix here.

How to Replace Paper Feed Rollers in HP M451 Series Printer

What is Actually Happening?
Everything that happens in a laser printer is timed to the millisecond. The image on the ITB “Intermediate Transfer Belt”, the position of the paper as it is being sent on its way through the machine and the timing of the laser are just a few of the many necessary events in the operation of a laser printer.
As the paper is being sent to the registration assembly the image is being created on the ITB. In this situation the paper never makes it to the Registration sensor (SR4). (Note: Misprint means paper jam)
Now, because that image is unusable the machine begins to clean the ITB which is the “Cleaning Mode”.
Then it will say “Misprint” and waits for the user to press “OK”. If you press “OK” the page that failed is reprinted. Then it will start the dreaded Loop of destiny.

The next solution is to replace the paper feed pick-up roller. It could be as simple as the roller is worn out and slipping. Rollers in a printer are similar to the tires on your car. If they are slick to can’t get traction, in the same way the roller can’t get the traction it needs to push the paper as much as it needs to go.

Sensor SR4 Registration
M451dn Sensor SR4 Registration

The problem is that the Paper Feed Pick-Up Roller does not push the paper far enough into the registration assembly. So how do we increase the amount/distance that this roller travels?  In this modification that I tried and have had 100% success with, we will increase the diameter of the roller. It is very similar to an adjustment that many copiers have. It is called the “Paper Feed Buckle” adjustment.  Here is an example of two different amounts of buckle as the paper is being fed into the registration rollers.

Paper Buckle Amount
Paper Buckle Amount
Paper Buckle Amount Increased
Paper Buckle Amount Increased

This would be great if that was all there was to it.  But I have had many that even though I replaced the roller it still had the problem.  That is why I had to come up with a fix or replace dozens of printers.  The following is how I increased the buckle amount by increasing the diameter of the roller.  I would love to hear from any people that had to perform my modification and how it turned out.
Drop me a line at izzykilman@gmail.com

Roller Modification
P/N
RM1-4426  Paper Pick-Up Roller
P/NRM1-4840  Separation Roller  (Change this roller at the same time).

IMG_0443
Feed Roller Modification: P/N  RM1-4426

IMG_0445
 Cut 6 strips of electric tape 85MM long.

IMG_0446
Stack them 1 at a time until you have all six
stuck together.  

IMG_0447
Trim off approximately 14MM doesn’t have to
be perfect.

Pull off the paper feed roller’s rubber only so that the half moon is showing. If you take it all the way off you may get the tread on backwards plus it’s easier not to.  Install the tape so that it covers the entire half-moon end to end.

Reinstall the rubber of the feed roller making sure it is straight and on correctly.
Compare rollers
Now compare the height of the rubber tread.  We have increased the diameter of the feed roller so that when it feeds the paper will travel further into the registration assembly and prevent the issues with cleaning/Misprint.

Note: If the roller is already worn out this wont work.

Reinstall the roller into the printer.

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