asked Dec 11, 2011 at 6:27am
Hp HP LaserJet 4

Toner on back

My trusty HP Laserjet 4 printer is applying a light dusting of toner on the back of each page. In addition to the light dusting it also prints (also on the back) a light horizontal line every 2.1 inches. Thorough vacuuming has no effect; pages look the same before and after vacuuming. Previous toner cartridges have leaked but this one does not. It is not an OEM cartdridge. Needless to say, any help would be greatly appreciated.
Only 2 places it can come from. The charge transfer roller that sits under the toner cartridge. Be real careful with that roller. No liquids, just wipe gently with a lint free cloth. The other place is the fuser pressure roller. That's the red roller visible at the bottom of the fuser. You can open the back door and see it. You can isolate it further by running a sheet from the MF tray. When the end of the sheet just starts to go in, open the door and remove the toner cartridge. Remove the paper and see if it's got toner on the back. If so, it's coming from the Charge roller, if not, the fuser.
by moe on Dec 11, 2011 at 9:06am Add comment
Did as instructed as see that there's some toner on the back although there doesn't appear to be as much as with a normal print. The charge transfer roller (which appears to be a foam roller?) seems to have a lot of toner on it. A gentle swipe and a paper towel comes away black even after vacuuming first. Is it supposed to be this way?
by deuxdad on Dec 11, 2011 at 9:30am Add comment
No. Clean it. As I said, be careful. The roller carries a High Voltage charge to charge the paper so the toner is attracted off of the drum.
by moe on Dec 11, 2011 at 11:28am Add comment
Does it have to be cleaned in place or can it be easily removed? In either case, how does one clean it? Thanks for the help BTW.
by deuxdad on Dec 11, 2011 at 12:39pm Add comment
You hook it under the shaft to the right of the blue gear. Lift up gently and slide it to the left and it will come out. Be real gentle removing and reinstalling as you don't want to break the mounts. Don't touch the surface with your fingers.
by moe on Dec 11, 2011 at 2:52pm Add comment
My apologies for taking so long to get back to this thread. I finally had to (once again) replace a fairly new toner cartridge whose photo-sensitive roller had become contaminated with something which prevented the wiper from removing the excess toner after each page. So, replacing the toner cartridge and cleaning the charge transfer roller (I always wondered why that little brush had such a big hook on the end) cleaned up the face of each printed page. The back of each page still has a light dusting of toner which I'm going to assume may be caused by the fuser. A project I'll tackle later when I figure out how to get to it.

Thanks again for the help.
by deuxdad on Jan 3, 2012 at 10:11am Add comment
Update: In reading forum posts regarding this problem I learned how easy it was to examine the fuser rollers. So I did. NASTY! I have just ordered part S100 fuser assembly.

On my way,
by deuxdad on Jan 3, 2012 at 10:55am Add comment