asked Feb 28, 2002 at 2:48pm
Hp HP DesignJet 100

Help w/Laserjet III strange printing behavior


I have a rather strange problem with my venerable old HP Laserjet III.
It has a somewhat intermittent (it will work for 100 pages, then
print funny for 200) problem with printing pages funny - banding is
the word I would use, but it's not banding in the traditional sense.
The bands are not constant between pages or even on one page. See the
pictures below for a better idea of what I mean. Sometimes the toner
is smeared in addition to this.

Pictures of my problem:

I have replaced both the fuser and the power supply (the PS needed to
be replaced anyways; the fan was dying). I don't think the fuser is
the problem anyways - there is never any "unfused" toner on the page.
I don't know that much about laser printers, but I'm thinking that the
problem may have to do with charging the sheet or the drum. The thing
is, you can *always* make out what was supposed to be on the page, so
the laser must be working fine. There's always a very light layer of
toner over what's supposed to be there - do you know what I mean? The
image is there. It's just not all properly "tonered" on there.

I have three different toner cartridges I have tested it with; one is
a genuine HP cartridge. None are new, but I don't think the problem
has to do with the cartridges. When the printer is printing funny, I
can switch out the cartridge and it will still print funny. When it
decides to print fine, I can switch out the cartridge and it will
still print fine.

The printer is clean inside, so far as I can tell. The engine test
works fine, except that it does the same banding thing.

Please help! What could the problem be? What parts should I try

Sounds like the high-voltage starting to go. RG1-0936-000CN. Chances are this will become a more frequent occurence as the hig-voltage takes a swandive.
by unknown on Feb 28, 2002 at 3:44pm Add comment
One would think so, but I just replaced the power supply with another one a few days ago, and the problem remained.
by JM on Feb 28, 2002 at 3:50pm Add comment
You need to get a better camera or fax me a copy of the page. Picture actually looked better with my glasses off. I'm hoping your fax isn't as bad as the camera. By power supply are you referring to the ac power module adjacent to the fuser? That has nothing to do with the high voltage. That power supply is the black one with the green dial at the opposite corner.
by moe on Feb 28, 2002 at 7:00pm Add comment
In this case, I'd first carefully clean the transfer corona wire, then I'd check the screws that are making the connections for the transfer corona and the HV power supply. I went on a call for a similar problem. I was going in after a tech worked on the machine for another problem. It ended up being the connections for the High Voltage supply. He had left out one of the screws and the connection was failing intermittently. The contacts that apply the high voltage to the cartridge could also cause something like this to happen.
by david belton on Mar 1, 2002 at 4:45pm Add comment