HP Laserjet 4000 paper jam and other issues.

[David Farber]

Initially there was a paper jam from the paper tray 2 which is the drawer
that slides into the bottom of the printer. I pulled out the paper and it
jammed again. The paper does not jam when fed through the foldout tray 1,
which is the combination envelope and paper feeder. When the printer is
powered up now, the display says, "Checking Printer," and blank paper starts
coming out. I believe this is a test that the printer makes to ensure the
jam is cleared up. However after four sheets of paper go through, the
display shows "Paper jam" again and it stops in mid cycle. Sometimes the
paper is not jammed but the display says it is anyway. The other malfunction
is that the pickup rollers for tray 2 are activated even if there is no
paper in the drawer. I found what was supposed to be the best solution here
http://h30499.www3.hp.com/t5/Black-and-White/HP-4000-checking-printer/td-p/4671668#.UvAcJFYmaSo
and here http://www.fixyourownprinter.com/forums/printer/68794. The fixes
made sense to me but it still is trying to pick up paper when it isn't
supposed to. I dismantled a good portion of the printer checking for
anything that might be causing it to jam but could not find any problem. I
tried this fix http://www.fixyourownprinter.com/forums/printer/27551 as well
with no success.

Thanks for your reply.
--
David Farber
Los Osos, CA

[Jeff Liebermann]

On Mon, 3 Feb 2014 15:20:07 -0800, "David Farber"
<farberbe...@aol.com> wrote:

>Initially there was a paper jam from the paper tray 2 which is the drawer
>that slides into the bottom of the printer.

Replace the feed roller RB1-8865 located above tray 2. If my
guess(tm) is correct, the printer has never had any of the rubber
parts replaced. Considering it's age, you might as well replace ALL
the rubber. Cheap enough:
<http://www.ebay.com/itm/320746402020>

>The other malfunction
>is that the pickup rollers for tray 2 are activated even if there is no
>paper in the drawer.

Congratulations. Your printer also has the HP exclusive sticky
solenoid problem. How to fix it on an HP2200, HP2300, HP4250, etc.
<http://www.learnbydestroying.com/jeffl/hp2200/hp2200.html>
<http://www.learnbydestroying.com/jeffl/hp4200/hp4200.html>
Unfortunately, I haven't bothered to make a web page for the HP4000
series printers. It's similar to the others except that the solenoid
is buried under additional layers of metal plates. I suggest you take
photos to help with the reassembly.
<http://marketpoint.files.wordpress.com/2011/03/lj40004100-025.gif>
Tear the printer apart. Find the sticky solenoids. Clean off the
sticky goo from BOTH the armature and solenoid core using solvent.
Apply thin felt as shown. Demagnetize the solenoid core if you
suspect that it's magentized.
<http://www.learnbydestroying.com/jeffl/crud/hp2200-solenoid.wmv>
Put Humpty Dumpty back together again. Be sure to thank HP for
ignoring the problem since the earliest HP laserjet printers.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[David Farber]

Hi Jeff,

I did clean (though probably not well enough) the sticky stuff off of the
solenoid which is used to control the lower "D" rollers. I used some
electrical tape as was suggested in the fix. Is the purpose of the felt or
electrical tape to muffle the sound when the solenoid is energized or is
there a mechanical reason as well? I'll take it out again, put some dc on
it, and see how it operates. I'll also replace the rubber parts.

[Jeff Liebermann]

Don't use electrical tape. My original version of the fix indicated
to use 2 layers of electrical tape. That worked for about 3 months,
when the tape got warm and fell off. I had to rework about 8 printers
where I had used tape. The felt has lasted much longer.

There are various thicknesses of felt available at the local hardware
store. The stuff in the photo is 2mm thick (including the backing
paper and NOT compressed). I also have some felt that's about 1mm
thick. Both work just fine but I would NOT go any thicker than 2mm.

The main purpose of the felt to reduce the sound, but it also may have
a secondary purpose. Running the solenoids off DC tends to magnetize
the cores. If the armature comes in contact with the core, it will
stick. See video at:
<http://www.learnbydestroying.com/jeffl/crud/hp2200-solenoid.wmv>
The felt provides the necessary air gap so that the armature doesn't
stick.

If replacing all the rubber parts and fixing the sticky solenoid
doesn't do the trick, there are some obscure problems that should be
investigates. The clutch that runs the feed roller (the one above the
paper tray) gets dirty and doesn't release. Tear it apart, clean out
the metal dust, and it should be ok. Another common problem is a
sticky paper height sensor. That's also above the tray. Clean with a
paint brush.

Good luck.

[David Farber]

"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:a733f9pk6s1oba16u...@4ax.com...

Hi Jeff,

I purchased the package of felt you suggested (picture at the bottom of this
page http://www.learnbydestroying.com/jeffl/hp2200/hp2200.html) and put it
on the solenoid. It was just the right thickness to allow the relay to
close. However after reassembly, the printer still was spitting out blank
pages. In other words, the solenoid somehow was not releasing. I did some
more web searching and finally found a link to the step by step procedure to
do the repair. Long story short, I finally realized I had pulled the wrong
solenoid. The one I was working on was for the upper tray #1, not tray #2
(the drawer that slides out). I went back to the service manual and figured
out how to get access to that solenoid. It was stuck shut of course. I
removed the stickiness from the components and put the felt on. For some
reason, this solenoid would not close when I manually tried to close it. The
felt was too thick. I removed the felt, put some electrical tape on it, and
now it works great. As for the electrical tape, if it fails again, at least
I know exactly where to find that solenoid. If anyone is interested, what
follows below is a very concise list of steps you can follow to get somewhat
easy access to the solenoid on the 4000 model.

Thanks for your help.

--
David Farber
Los Osos, CA

From
http://www.petri.co.il/forums/showpost.php?s=d0803b95688f2018c531d8c0cbc0d171&p=262315&postcount=6

I found that accessing the solenoid is much less complicated than described
above.
1- You only need to remove the rear right side cover. Just slide it to the
rear.
2- Remove the formatter assembly, the formatter pan and unplug the large
cable that is behind the pan and remove the cable wire bundle from its
retainer.
3- Open Tray 1 on the front and unscrew 2 long screws that attach the
printer to the Tray 2 assembly; they are located on each side of the Tray 1
pickup assembly. (They are 4 1/2 inches long and oriented in an upright
position) They are not easy to see on first inspection. The left one is
recessed in a hole on the left side. The right one is behind a cover which
you can flip open on the right side. The left screw can be left in place
once it is unscrewed.
4- Remove the screw that is on the left side of the printer just below the
cooling fan. There is a hole in the left cover specifically for this
purpose.
5- Lift the printer straight up off of the Tray 2 assembly. This is about
2/3 of the total unit and will lift off easily.
6- Remove the cover plate on the Tray 2 assembly.
7- Loosen the Tray 2 gear train assembly from the Tray 2 housing. There is
just one screw holding it in place and this screw is recessed in the inner
right side. Make sure to first remove the solenoid wires (2 wires) from
their routing channel before removing the assembly. I would NOT recommend
unplugging these wires from the controller as they are small and seem
fragile.
8- Lift out the gear assembly. The solenoid is now available to remove and
service. Make sure to remove all of the glue residue. I found the glue to be
quite tenacious and required extra care to remove it all.
Just 2 notes on reassembly:
1- Take care to be sure that the solenoid is well seated in its proper
position when screwing it back on.
2- When placing the printer back on the Tray 2 assembly, check that the
large cable is out of the way.

[Jeff Liebermann]

On Sat, 8 Feb 2014 16:30:39 -0800, "David Farber"
<farberbe...@aol.com> wrote:

>I finally realized I had pulled the wrong
>solenoid. The one I was working on was for the upper tray #1, not tray #2
>(the drawer that slides out).

Oops. The URL I supplied was for the Tray 1 solenoid.

>I went back to the service manual and figured
>out how to get access to that solenoid. It was stuck shut of course. I
>removed the stickiness from the components and put the felt on. For some
>reason, this solenoid would not close when I manually tried to close it. The
>felt was too thick.

Hmmm... That's odd. I've been using the 2mm thick felt for HP
solenoids without difficulties. There is a solenoid in the HP2550n
color laser that requires 1mm thick felt, which I was able to find at
the local $1 store.

The neighboring office has an HP4000 that is going to the recyclers
shortly. I'll take a closer look at the solenoid (time permitting).

>I removed the felt, put some electrical tape on it, and
>now it works great. As for the electrical tape, if it fails again, at least
>I know exactly where to find that solenoid.

If my experience is any indication of future performance, the glue
will either melt or evaporate. Old electrical tape becomes brittle
and non-sticky after a few years. Either way, I believe that the
electrical tape will eventually fall off. I predict you'll be digging
in again in a few months.

Did you check for a magnetized solenoid?

>If anyone is interested, what
>follows below is a very concise list of steps you can follow to get somewhat
>easy access to the solenoid on the 4000 model.

Thanks. I'll plagiarize it for when I eventually do an HP4000
instruction page.

>Thanks for your help.

Congrats and sorry for the confusion.