M602 Fusing issues

[whatwave]

I have an M602 that does very long print jobs.

Intermittently there was small black marks near the bottom of the page. The marks were almost all the way across the page.  No co-relation to anything printed on the page and not repeated on the page. Usually happened several pages in a row and sometimes there was a darker box near the top of the page prior to this happening.

Found a small deposit of toner, on the bottom of the toner case right after the drum. This deposit seemed to match the intermittent mark on the bottom of the page. Swapped toners with an identical printer and the problem stayed with the printer. Thought the issue must be the fuser, as they had a couple of paper jams as the paper entered the fuser, and maybe the paper jamming had deposited the toner on the toner case.

Replaced the fuser and that seemed to resolve the issue.

But.....several weeks earlier, usually during long print jobs, some pages would not fuse or parts of pages would fuse. Due to the size of the print jobs (sometimes thousands of pages) it wasn't always noticed and it was difficult to notice without checking the full job. I was never able to resolve this issue and it seemed to disappear on its own accord.

Since replacing the fuser for the small deposits of toner, this problem has come back intermittently. The latest time it happened seemed to be right after the paper was changed in the middle of a job. Confirmed the fuser was seated properly, no errors in the log, nothing unusual that the customer noticed.

Have I got a replacement fuser that is bad?

Is this an intermittent high voltage board failure?

Firmware is at 3.2.7

Any suggestions?

[tonerspills]

I can put forth a few suggestions that might point to the cause of the issue. Are you using a non-OEM toner? HP printers have a pretty specific toner formula- so a non OEM cartridge could contain a toner that is not bonding properly, or could be leaking in the machine- this might explain why you are seeing toner buildup under that cartridge near the transfer roller (the spoungey roller under the cartridge- dont deform it or get any moisture on it!)- this toner buildup does occur a little with HP cartridges as well- just generally not as bad-

I would suggest updating the firmware to the latest version located here. Just choose your correct operating system. There have been firmware updates related to the performace of the engine and fusing system, so that could be contributing to the problem.

Also, if you are running very large jobs in the thousand of pages, that may be pushing the printer to its operational limits. The fusing unit could be overheating to some extent. I could see where residual heat inside the machine from a prolonged print run could trick the temperature sensors into thinking the fuser is warmer than it actually is, so the rollers arent as warm as they think they are, contributing to poor fusing. Also if you've run over 500-750k pages, the fuser drive gears could be starting to wear.

My suggestion would be to update the printer firmware first and see what happens- If the print jobs are thousand of pages, you may need to pause the machine from time to time to allow it to cool a litte- you may even want to take that cartridge out and give it a good shake or two, and clean the area underneath it.

[whatwave]

Thanks for your response and ideas.

Sorry for the delay getting back, as the issue only seems to happen with very large print jobs and is intermittent.

We are using original HP toner cartridges.

We have 2 identical HP LJ M602 printers in the same room. The LH printer is reserved for the very large jobs and the RH is for all other jobs.

At present, have not updated the firmware, but confirmed the firmware versions are the same on both printers.

As a quick test, we swapped the fusers between these 2 printers. Since that time, we've had 2 large jobs on the LH printer and the RH printer has done its day to day printing.

We've had no issues since the swapping of the fusers.

What we're thinking, is the fuser that is in the RH printer, may have an issue when running large jobs. Maybe it has to cool down like you suggested.  This was a replacement fuser due to another issue with the fuser in the LH printer.

We'll wait for a few more large print jobs to go through without issues before we try swapping the fusers back.

[fuserlife]

Just thought i would mention i had the same issue and i think i have solved it now.

Basically TLDR, the plain paper is set to "light" by a previous bad firmware. You need to set it to normal.

This is why we had a loaner printer do the exact same thing, and why throwing fusers at it (as i was about to do!) will not help.

ref: http://lbrty.com/tech/articles/m600/m601_fusing.html

ref: http://www.enxmag.com/twii/tech-tip/2018/02/ghosting-smudging-or-not-fusing-properly-on-plain-paper-...

Identify if the Paper type for “Plain” paper is set to “Normal”

How to check and change Paper Type “Plain” from “Light” to “Normal.”

NOTE: This can be done at the printer’s control panel or through EWS (Embedded Web Server).

Using printer’s control panel:

With the printer turned on, press the following buttons:

1. Press the Home button on the control panel that looks like a little house.
2. Press the down button until “Admin” is reached, then press “OK.”
3. Select “General Settings” then press “OK.”
4. Select “Print Quality” then press “OK.”
5. Select “Adjust Paper Types” then press “OK.”
6. Select “Plain” then press “OK.”
7. Select “Print Mode” then press “OK.”
8. Select “Normal” then press “OK.”
9. The new setting is now saved and you can now press the Home (Little house) button to return to main screen.
10. Turn the printer off then back on again and you can start printing again.

Using EWS (Embedded Web Server):

1. Select “General tab”
2. “Control Panel Administration Menu”
3. “Administration”
4. “General Settings”
5. “Print Quality”
6. “Adjust Paper Types”
7. Click on “Go to Primary Setup Page”
8. Select “Plain”
9. Click on “Modify” at bottom of page
10. In the Print mode box if it says “Normal” then no change is needed If it says “Light Mode,” then select the drop down arrow and select “Normal” and then click on “Apply”