Laserjet III feed roller working better than it should

[Z-ster]

In contrast to what's usually the problem with the old LaserJet III (not
picking up the paper from the tray) I have the opposite problem.

My printer picks up the paper from the tray and transporting it to the
registration rollers and then continues rolling causing the paper to fold
back on it's self and eventually jam. The solenoid that engages and
disengages the freed roller is working to engage but I can't understand why
the controller doesn't stop after one revolutions. I assume the feed roller
only required one revolution before the paper comes in contact with the
registration rollers.

Are there any paper sensors which tell the controller to disengage the
solenoid for the feed rollers? I physically searched but can't seem to find
any.

Although it could be the controller that's to blame I don't understand why
it would work for engaging the solenoid but not disengaging it. That is why
I'm thinking (hoping) it might be something else.

Any ideas?

Thanks,

John.

 

[DaveG]

Sometime on Mon, 05 Dec 2005 11:53:40 +1100, Z-ster scribbled:

In contrast to what's usually the problem with the old LaserJet III (not
picking up the paper from the tray) I have the opposite problem.

My printer picks up the paper from the tray and transporting it to the
registration rollers and then continues rolling causing the paper to fold
back on it's self and eventually jam. The solenoid that engages and
disengages the freed roller is working to engage but I can't understand why
the controller doesn't stop after one revolutions. I assume the feed roller
only required one revolution before the paper comes in contact with the
registration rollers.

Are there any paper sensors which tell the controller to disengage the
solenoid for the feed rollers? I physically searched but can't seem to find
any.

Although it could be the controller that's to blame I don't understand why
it would work for engaging the solenoid but not disengaging it. That is why
I'm thinking (hoping) it might be something else.

Any ideas?

Sounds like the solenoid is sticking. I think it's a spring return on
those ones so it might just need a clean and lube. The feed roller is
driven by the main gear train while the solenoid is engaged. If it
sticks, the feed roller keeps turning.

 

[Z-ster]

Sometime on Mon, 05 Dec 2005 11:53:40 +1100, Z-ster scribbled:


Sounds like the solenoid is sticking. I think it's a spring return on
those ones so it might just need a clean and lube. The feed roller is
driven by the main gear train while the solenoid is engaged. If it
sticks, the feed roller keeps turning.

Yep, that correct, however I can't see how it could stick because the spring
has quite a bit of force.
Besides, when the print job has ended the solenoid disengages.

 

[Silicon Sam]

I fixed MANY of those with that problem. There is the selenoid with
a flapper on it to allow the pickup roller to rotate 1 time. The
flapper has a foam pad on the bottom side that keeps it from making a
loud CLICK everytime the selenoid engages. After a long time, the foam
turns to mush and gets real sticky. The selenoid fires, the flapper
stays stuck to the selenoid after the selenoid releases it. Allowing
the pickup roller to keep turning longer than it is supposed to.

Take the selenoid out, take the flapper off, clean off the gooey
mess, and either replace the pad with something else, like I did, or
live with the noise. I can't recall what I used, but it has to be thin
so the selenoid still works..

Raymond

 

[DaveG]

Sometime on Mon, 05 Dec 2005 16:38:08 +1100, Z-ster scribbled:

Yep, that correct, however I can't see how it could stick because the spring
has quite a bit of force.
Besides, when the print job has ended the solenoid disengages.

It sticks and takes a little while for the force of the spring to pull it
back. But during a print job the power to re-engage the solenoid is
applied before it can free itself so it stays stuck. After the print job
finishes it has time to disengage.

 

[Z-ster]

Sometime on Mon, 05 Dec 2005 16:38:08 +1100, Z-ster scribbled:


It sticks and takes a little while for the force of the spring to pull it
back. But during a print job the power to re-engage the solenoid is
applied before it can free itself so it stays stuck. After the print job
finishes it has time to disengage.

you've been most helpful.

This sounds like it might be the cause of my problem

 

[Z-ster]

I just check it without pulling apart the whole printer by pressing it up
against the solenoid with a screw driver and bit of force and sure enough it
stayed stuck for about a second.

So I'm guessing with the greater magnetic force of the solenoid it would
remain stuck there longer and enough to cause the problem.

Thanks again.

 

[Silicon Sam]

Yes, but it has nothing at all to do with the spring. The spring is
fine and doing it's job. Clean out the muck under the flapper and
you'll be fine.

Raymond

 

[DaveG]

Sometime on Mon, 05 Dec 2005 20:31:03 +1100, Z-ster scribbled:

I just check it without pulling apart the whole printer by pressing it
up against the solenoid with a screw driver and bit of force and sure
enough it stayed stuck for about a second.

So I'm guessing with the greater magnetic force of the solenoid it would
remain stuck there longer and enough to cause the problem.

Glad to hear it. Clean out the dirt and lube it and you'll be good to go


They might not be high quality or as efficient as todays new laser
printers but those old III's were built like tanks and will probably go
for a few more years yet.

The worst problem I ever came across was replacing the lower fan. It's a
bugger to get to. It the same type as the top one. Toroidal?
Centrefugal? Whatever! It's a spinning drum rather than a spinning disk
LOL. The aftermarket spares eventually changed to an 80mm(60? 40?)
standard fan in a special housing because the rubber/metal bearing/mount
on the original would wear out and the drum fan would wobble loudly before
failing.

 

[Z-ster]

Yes, but it has nothing at all to do with the spring. The spring is
fine and doing it's job. Clean out the muck under the flapper and
you'll be fine.

Raymond

Sorry about not being clear in my previous post. I meant to say the
magnetising force of the solenoid is greater than the pushing I did with the
screw driver (as a test). Therefore during printing it would stay stuck
against the soft mushy rubber/glue longer than it did with the screw driver
test which only remained stuck for about a second.

Anyway, I've now cleaned off all the glue and foam, on both solenoids and it
works like a treat So simple yet it had me stumped.

All is now good thanks to you guys

Cheers,

John

 

[Z-ster]

Sometime on Mon, 05 Dec 2005 20:31:03 +1100, Z-ster scribbled:


Glad to hear it. Clean out the dirt and lube it and you'll be good to go


They might not be high quality or as efficient as todays new laser
printers but those old III's were built like tanks and will probably go
for a few more years yet.

The worst problem I ever came across was replacing the lower fan. It's a
bugger to get to. It the same type as the top one. Toroidal?
Centrefugal? Whatever! It's a spinning drum rather than a spinning disk
LOL. The aftermarket spares eventually changed to an 80mm(60? 40?)
standard fan in a special housing because the rubber/metal bearing/mount
on the original would wear out and the drum fan would wobble loudly before
failing.

Well I'm hoping to have trouble free service for a while longer now that
I've fixed this problem.

Thanks again...

Cheers,

John.

 

[Silicon Sam]

The lower fan is the easiest fan to get to. Flip the printer upside
down (after removing the toner cartridge), take out the screws holding
the bottom pan on, unscrew the fan. Only 1 part needs to come off to
get to it. 2 if you include the plastic cover on the /// series.

Not always the same type. The upper fan is either a squirrel cage,
or axial fan, or can be the pancake type you normally see everywhere.
The axial has a problem with bushings going dry.

Glad it's fixed. I hav e lots of spare parts I am dumping cheap soon!

Raymond