HP Laserjet 1220 & black dots

[Sami]

I was given a HP Laserjet 1220 which has a problem. There are little black
dots randomly printed over the paper. In the center area there are a little
bit more of these dots than in the edges. I tried the cleaning procedure
where the printer feeds the paper slowly through the printer but it did not
help.

I wonder if there is dirt in the glasses/lenses of the Laser/Scanner unit or
could this be a power supply problem?

The quality of the printouts is good except these dots.

-Sami

 

[Tony]

Sami
What you describe sounds like toner scatter which is almost always a toner
cartridge problem. Do you have a spare cartridge since that is the easiest way
to prove it?
Also, if I remember correctly this printer has a scanner, if so does the
problem occur with only scanned images?
The best test you can perform is a "half test".
Print a page, either an internal printer test page or from the PC, as the page
feeds open the front cover when the trailing edge of the paper has just
disappeared into the printer.
Remove the toner cartridge, don't pull the paper out yet, and examine the page
in the printer, are the dots there on the paper? If they are there the
cartridge is at probably at fault. The page will have unfixed toner and will
smudge, this is quite normal. You may have to do this a few times to get the
timing right, the paper should have stopped with a portion of it under the
cartridge and that is the portion you need to look at.
If the dots are not on the paper during the you need to determine whether the
dots really are random. Random dots often turn out to be otherwise after
careful examination.
You need to pick on one dot near the top, look down and does it repeat exactly
below the original location and then does it repeat again (maybe several
times)....is the verticlal distance between each of these dots the same. If so,
measure that distance precisely and post the measurement here. It needs to be
measured to the nearest 1/16" or 1mm. Don't be distracted by dots that are not
exactly below the first.
If the Laser scanner was at fault you would be missing detail, rather than
picking up extraneous dots. A high voltage power supply problem is unlikely to
cause this fault.
Let us know how you get on.
Tony

 

[Sami]

Sami
What you describe sounds like toner scatter which is almost always a toner
cartridge problem. Do you have a spare cartridge since that is the easiest way
to prove it?
Also, if I remember correctly this printer has a scanner, if so does the
problem occur with only scanned images?
The best test you can perform is a "half test".
Print a page, either an internal printer test page or from the PC, as the page
feeds open the front cover when the trailing edge of the paper has just
disappeared into the printer.
Remove the toner cartridge, don't pull the paper out yet, and examine the page
in the printer, are the dots there on the paper? If they are there the
cartridge is at probably at fault. The page will have unfixed toner and will
smudge, this is quite normal. You may have to do this a few times to get the
timing right, the paper should have stopped with a portion of it under the
cartridge and that is the portion you need to look at.
If the dots are not on the paper during the you need to determine whether the
dots really are random. Random dots often turn out to be otherwise after
careful examination.
You need to pick on one dot near the top, look down and does it repeat exactly
below the original location and then does it repeat again (maybe several
times)....is the verticlal distance between each of these dots the same. If so,
measure that distance precisely and post the measurement here. It needs to be
measured to the nearest 1/16" or 1mm. Don't be distracted by dots that are not
exactly below the first.
If the Laser scanner was at fault you would be missing detail, rather than
picking up extraneous dots. A high voltage power supply problem is unlikely to
cause this fault.
Let us know how you get on.
Tony

Thank you for comprehensive answer. The dots appear both in scanned and
testpage printouts. The dots are very small ( smaller than 1mm) and there
are thousands of them in the prints. I'll try the "half test" tonight and
let you know the results. Unfortunately I don't have a spare toner.

-Sami

 

[Sami]

You were right. The problem was the toner cartdridge. I installed a new one
and the dots were gone. Now there's only a slight problem left. The paper
doesn't go straight through the path and therefore there is about 3mm
misaligement in the printout. It seems that the paper turns a little almost
immediately after it is sucked in the printer. I will try to figure out, why
does this happen...

-Sami

 

[Tony]

Sami
That is good news.
The paper feed problem is probably the paper pick up roller.
You can easily remove it.
Take the cartridge out. You will see the roller towards the front of the
printer, it will be light gray.
On top of the roller at each side is a little white clip, gently press these
clips outwards and the roller will spring up a little, rotate the roller
towards you and it will lift out. No force required.
You can clean the rubber with a damp cloth or isopropyl alcohol. Put it back
the way it came out, it will only go one way so no force is necessary.
If that fixes it then fine, if it improves it but does not completely fix it
then you need a new roller. You will probably need one at some time soon anyway.
If you are getting more than one page fed at a time then you need to replace
the separation pad underneath the roller but that is trickier to do. Let me
know if you need further assistance
Tony