hp lj 2420d repeating defects

[MLS5262]

I am working on a HP LJ2420 that has repeating images down the center of the page 35mm apart. The fuser has been replaced, because it had other problems, but the repeating image remains.

performed a half-way test and the image is forming before the fuser.

- tried two new hp toner cartridges, no change.
- replaced the transfer roller, no change.
- checked grounding contact lever to see if it had come unhinged, it is ok, no change.
- updated firmware, no change
- replaced power supply, no change
- replaced formatter, no change
- replaced ECU, no change

I'm probably missing something simple, but would appreciate some input.

thanks

[cs_steve]

Did you try a second fuser just to be sure? Do you have a machine you can test the current fuser in?

[MLS5262]

I haven't tried a different fuser and unfortunately do not have another one available to test with. The half-way test shows the repeating mark before it enters the fuser.

[MichaelTech]

Uh,,, the "pick-up roller"?
or, the paper has something on it, like a spot of oil?

[MLS5262]

no, it definately is a repeated image, you can see words from earlier on the page sometimes.

good suggestion though.

[Big Al]

When you swapped the formatter did you also swap the memory DIMM?
We have changed a few but they did not work at all. There is a section
of these DIMMs that act as a RAM drive. Sorry, grasping at straws, but
it is the only thing left that I can think of.

Al

[MichaelTech]

At 38mm, it would be the toner for sure. OEM toner? There's a lot of 3rd party toners that fail a lot.
Run a cleaning page even though it's not the fuser. Bumps up the voltage a bit, and may clear the problem up.

[cs_steve]

Sure your toners aren't counterfeit HP? buying from reputable source?

You said you replaced the fuser because of other problems? What were those?

[MLS5262]

Sorry for the delay in replying, had other fires to put out.

when I swapped the formatter, I put the original DIMM in the new formatter. currently don't have one to replace it with.

the toner cartridges were brand new hp toners, with the marks being 38mm apart, which indicates the primary charging roll being the issue. the original toner and two new hp cartridges gave the same issue. we have tried running the cleaning page, but it didn't help either.

the heat roller was breaking apart, replacing it corrected part of the problem, but the repeating mark still remained.

thanks for your replies
Merry Christmas to all

[redcow]

Did you try running the half test?