asked Feb 28, 2005 at 6:17pm
Hp HP LaserJet IIIP+

HP 3P grey background

I was advised to post my problem in this section of the forum. It was previously posted elsewhere and I just cut and pasted the text.
I was asked to do the half print test and I have added my response to that as well.

The thread as it started

I have aquired a HP IIIp laserjet it prints grey background and
normal text (print test mode not connected to PC). I have tried
another toner cartridge with the same results.

I can cleaned the drum and rotate it by hand and it stays clean,
however when the page prints I get a grey background and examining
the drum it has toner over it. I've tried adjusting the light/dark
setting but no change. Any suggestion as to the problem.

I did the tests as you describe and the middle section is grey with
the test text.

I do not have any manual for the 3P and it looks like a bit of an
effort to get to the mirror assy/scanner.

As I said in a previous post I printed a page and then examined the
drum and it had a coating of toner on it.

Is this normal.

As I understand it the toner is only picked up by the drum where the
text should be and this text is the area on the drum that has not
been discharged ie the laser is turned off where the text should be
and on everywhere else to discharge the drum.

If the drum has a layer of toner still on it and also the test text
am I correct in saying that the laser is not doing its job of
discharging the drum correctly either by being low in emmission or
dirty mirrors, but still scanning the drum and turning off correctly
where the text is to be written thus the scanning section is ok.

The fact that toner is on the drum would indicate the corona charge
area is working ok, and the fact that I don't get repeat print
indicated the static discharge side is working ok.

I think I need to inspect the mirrors.

Does anyone have the pages from the 3P maunal that describes how to
access this mirror area.

Thanks again



That toner cartridge is a bear. I have seen more bad ones out of the box then any other. My gut feeling is you still have a bad toner cartridge. If you are using remanufactered ones I would try to get a new oem or order one from Moe at this site. The key is the toner on the drum. Only place that toner can come from is the toner cartridge itself.
by dmzcompute on Feb 28, 2005 at 7:47pm Add comment
I understand what you are saying I've tried two toner units one was an OEM with the same result. However if I clean the drum I can rotate the drum by hand until the cows come home and there is no toner residue on the drum.

Is it not the job of the corona unit to electrostatically charge the drum and the job of the laser to cancel out the charge except where the print should be (laser turns off where the print is). If the laser was low power or the mirror assy was dirty preventing full laser power to discharge the charge on the drum, then the toner would be picked up in various degrees and coat the drum.

Is there any way of checking the laser power.

by Anonymous on Feb 28, 2005 at 8:05pm Add comment
That is because there is a wiper blade in the cartridge which removes the toner which was not transferred to the paper. If the wiper blade is failing the residue toner will come around again not as a repeat image but smeared over the whole drum by the bad wiper blade. When you clean the drum, there is no toner left when it comes around again.
by dmzcompute on Feb 28, 2005 at 8:48pm Add comment
Let me give you an understanding of how it works. The drum surface is charged by high voltage. Wherever the laser writes is where the voltage is discharged and that is where the image is formed. If the mirrors or any part of the optics were dirty, it would result in lessening the reflected laser output to the drum. The only effect this would have is light printout. Your problem is 100\% a high voltage issue, nothing to do with the laser. The charge roller can be ruled out since all that does is transfer the existing toner that is on the drum to the paper. It can't add something that's not there. Since you did use an OEM cartridge, about the only thing left would be the high voltage power supply or the contacts to the cartridge. The contacts are located on the left side of the printer. Usually, lack of connectivity will cause black bars or black pages. I've never seen it cause gray pages, but anything is possible. Remember, it's lack of charge that causes toner to stick to the drum. Here's a picture of the contacts taken from the "competition's" site I'd advise you not to ask him anything as he's hostile to customers.

by moe on Feb 28, 2005 at 10:30pm Add comment
Simple test. Remove the toner cartridge and do not wipe the drum. Rotate the drum 360 degrees and see if the residual toner which was on the drum when you took it out is still there. If it is, the toner cartridge is the issue. If not I would lean towards Moes answer. After Moe is the expert.
by dmzcompute on Mar 1, 2005 at 4:35am Add comment
I was under the impression that the corona assy static charged the drum to 600v and the laser discharged the drum to about 100v, the toner would be attracted to the area of the drum that is statically charged. The laser acts as to produce a negative image that is it discharges the drum (laser on)except for where the toner/text is to be laid down (the laser is turned off). The drum picks up toner where the static charge remains it is then statically discharged after the paper (which is also static charged) has passed the drum and the scrapers finish off the job before the cycle begins again. OR do I hve it all wrong?


by Anonymous on Mar 7, 2005 at 11:29am Add comment
Seen this problem several times before.

either too much toner so the background is gray, or not enough and the actual real print is faded and messing with the density settings does nothing.

you have a defective HVPS. From what i remember it was kinda hard to get too, a LOT of disassembly. It sits in a black sled under everything else.

good luck.
by jvilla on Mar 8, 2005 at 9:03am Add comment
listen and learn:

I bought a reman/refilled '75A cartridge off the 'net. After four pages, all printed output was covered with grey smeared background. Under the shutter, the green drum was covered in toner dust. I was upset. I searched and read through this site. Obviously the cart had a worn wiper blade that wasn't replaced.

I went out and bought a new original HP 75A cart from a local office superstore. It cost more than twice the price as the online bargain. Installed it and print quality is as good as new.

I am happy again and I love my HP LJ3. Thanks, Moe.

What an unfortunate waste of my time and my $$ letting myself get misled into thinking I was getting a deal.
by Anonymous on May 3, 2006 at 7:30pm Add comment