On 09/11/2017 06:00 PM, Jeff Liebermann wrote:
On Mon, 11 Sep 2017 16:17:07 -0400, "Percival P. Cassidy"
wrote:

Jeff: I don't see anything recent by you on comp.periphs.printers, so
I'll ask here on sci.electronics.repair:

That's because I don't read comp.periphs.printers.

I have a LaserJet 2200DN that is having trouble with duplex printing:

I followed your procedure that I found online

That would be:
http://www.LearnByDestroying.com/jeffl/hp2200/hp2200.html

and removed the sticky
goop from the solenoid you highlighted as the main problem, and used a
piece of that thin adhesive-backed felt, but I checked the other two
solenoids and determined that they were not sticking.

How did you determine that? The printer is at least 10 years old. By
now, I would expect the foam on all three solenoids to have
devulcanized into a sticky goo. Even the slightest release delay
caused by the sticky goo will cause problems. At this point in time,
it is better to just assume that all 3 solenoids need cleaning and new
felt.

I moved the armatures until they touched the foam pads, and there was
not the slightest sign of sticking.

You should have taken out all 3 solenoids, cleaned off all 3
solenoids, and applied the replacement felt to all 3 solenoids. Only
this solenoid:
http://www.learnbydestroying.com/jeffl/hp2200/HP2200-04.jpg
causes it to paper jam or feed more than one page, but if the other
stick, there can be other problems.

You should also have checked if any of the solenoid cores are
magnetized. They get that way after many years of operation.

No sign of permanent magnetism in any of the solenoids.

Since all this was in my instructions, I suggest you re-read the web
pages and please follow them this time.

The first double-sided document I printed -- a single sheet -- printed
fine, but trying to print multiple copies produced a paper jam, with a
sheet sticking out partway -- on the point of feeding back in to print
the second side -- and a sheet in the duplexer tray.

That is the classic symptom of a paper jam caused by sticky solenoids.
However, it is also a fair description of what happens when the
separation pad (RB2-6474) is worn out or filthy. I suggest getting a
"paper jam kit" or "maintenance kit" and do a general cleaning. It's
cheap and easy. Something like this:
http://www.ebay.com/120894286540

Those parts were replaced a few months ago. That solved the problem that
it kept trying to pick up several sheets at once.

Subsequent attempts to print even just one double-sided legal sheet
result in a jam: the paper seems to be on the point of feeding back in
to print the second side, but there is a "chattering" sound, and the
paper can be pulled out easily. If I try with a letter-size sheet, no
paper sticks out: the edge is just visible when I open the back -- same
when I do the Engine Test.

Sometimes there is a "ch-ch-ch-ch" sound just after I turn the printer
on -- a sound that I do not recall previously.

There should not be any ratcheting sound when you turn on or run the
printer. I can't tell from where exactly what's wrong, but you may
have reassembled the printer incorrectly after cleaning the solenoids.
It could also be one of the other solenoids sticking. Use a
stethoscope to locate the source of the noise.

I wouldn't really call it a ratcheting sound. It's much softer and
"gentler" than that. More like parts rubbing together.

Also, my favorite screwup is re-installing the solenoids at an angle,
and then locking them down with the retaining screw. It looks right,
but it won't work. Loosen (not remove) the solenoids and rotate until
the hole in the frame aligns with the locating pin.

The only solenoid I removed was the first one, the one that did have the
sticky goo problem. I was very careful to position it correctly when I
reinstalled it.

Before I "attacked" the solenoid, the machine would jam with the paper
sticking out further from the normal output slot, and with the leading
edge of a page about even with the black roller.

The distance between the first and 2nd page is a function of how
sticky the solenoid might be. The longer the distance, the more
sticky.

Could some parts of the mechanism have become "unsynchronized" while the
plate with all the gear wheels was removed and when activating the
solenoids enabled springs to turn gear wheels and shafts? -- I did turn
them back to the point where the solenoids were preventing them from
turning by the spring action.

No. The various rotating shafts are self aligning. As long as you
didn't take apart one of the clutches on the rotating shafts, it
should align itself.

I'd be grateful for any assistance you could provide.
Perce

Good luck.