LJ II engine question

  • Thread starter Thread starter Duane Bozarth
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Duane Bozarth

Have old QMS PS810 (same engine as HP LJ II) which isn't fusing
properly. Is the fuser assembly the only cause? IOW, if it still
functions otherwise, and I get the roller repair kits as well while I'm
at it, what other diagnostics/tests do I need to do so I go ahead and
get everything at one go?
 
Duane said:
Have old QMS PS810 (same engine as HP LJ II) which isn't fusing
properly. Is the fuser assembly the only cause? IOW, if it still
functions otherwise, and I get the roller repair kits as well while I'm
at it, what other diagnostics/tests do I need to do so I go ahead and
get everything at one go?
Click to expand...


There are some web pages on various page defects for laser printers.

You can probably find them by a Google search.

These images will help you identify better the source of your problem.

What does it mean.... "... isn't fusing properly....."

It could be that the fuser heater isn't getting hot enough to properly
melt the toner..... and yes, that should be taken care of with a rebuilt
fuser (it is quite a pain to replace the heater yourself).
 
Isn't fusing properly isn't very specific. Is it fusing at all?
First thing is the fuser lamp coming on in short bursts, and is the
toner being fused to the paper, or does it (on exit) smudge with
your finger? Just had to fix my fuser lamp (opto-coupler and
triac) driver.
 
Isn't fusing properly isn't very specific. Is it fusing at all?
First thing is the fuser lamp coming on in short bursts, and is the
toner being fused to the paper, or does it (on exit) smudge with
your finger? Just had to fix my fuser lamp (opto-coupler and
triac) driver.
Click to expand...

Granted, was hoping to get some pointers for
checking/testing/diagnosing...

It fuses partially but is smudged (lengthening of characters, etc.) and
is not fully (but is partially) fused to the paper so it isn't totally
<un>fused. I'm unaware of precisely how to tell at what fraction the
lamp is/is not on. For certain the temperature of the exit page isn't
as high as it should be.

fixyourownprinter.com had lists of kits, etc., but didn't find much on
diagnosing...

Thanks for any pointers...while ancient, this printer hasn't had that
many sheets through it over it's lifetime. It's slow by today's
standards but is there a comparable PS laser out there these days? Ink
jets are cheap but a pita for infrequent use as the d---d cartridges dry
up/clog and never work when wanted...
 
It fuses partially but is smudged (lengthening of characters, etc.) and
is not fully (but is partially) fused to the paper so it isn't totally
<un>fused. I'm unaware of precisely how to tell at what fraction the
lamp is/is not on. For certain the temperature of the exit page isn't
as high as it should be.
Click to expand...

If as I think, it's a Canon SX engine, flatbed, clamshell design, with
a flap that can be lowered, then you can look through the exit flap,
better in a dim room, and see the fuser lamp going on and off. At
start up (from cold) it comes on for about 30 secs, then once
warmed up for around 3 to 5 secs per minute. The lid needs to be
closed so you have to view via the exit flap, though I think it's
not too difficult to make an interlock cheater. From the back, I
found looking to the right (left side of printer from the front) worked
best.

For the SX there is a well documented capacitor problem, on a
board that is part of the AC power supply, which also houses
the power triac, that turns the fuser lamp on and off, and the
opto-switch that turns it, the power triac, on/off. The capacitor
leaks a mildly corrosive electrolyte after a few years.

Parts to fix at component level are cheap. 500W fuser lamp, linear
quartz halogen, 5 UKPDS about 8 USD, triac a bit less, same for
opto-coupler, even less for capacitor. The carriage cost me more
than the parts. You need to be a techie to dismantle and replace the
parts. There are online manuals and repair instructions, but you
need to be familiar with desoldering components.

To replace assemblies, both the AC power supply and the fuser
are on four screws, though you need to take the cover off.
I'd guess that your fuser is producing some heat, as the machine
should give a fault indication if it doesn't see the fuser heating up
at all. Old age can cause the pins of the modules to freeze in
place and it may require more major dismantling to free them
up. Excessive force is contra indicated.
 
If as I think, it's a Canon SX engine, flatbed, clamshell design, with
a flap that can be lowered, then you can look through the exit flap,
better in a dim room, and see the fuser lamp going on and off. At
start up (from cold) it comes on for about 30 secs, then once
warmed up for around 3 to 5 secs per minute. The lid needs to be
closed so you have to view via the exit flap, though I think it's
not too difficult to make an interlock cheater. From the back, I
found looking to the right (left side of printer from the front) worked
best.

For the SX there is a well documented capacitor problem, on a
board that is part of the AC power supply, which also houses
the power triac, that turns the fuser lamp on and off, and the
opto-switch that turns it, the power triac, on/off. The capacitor
leaks a mildly corrosive electrolyte after a few years.

Parts to fix at component level are cheap. 500W fuser lamp, linear
quartz halogen, 5 UKPDS about 8 USD, triac a bit less, same for
opto-coupler, even less for capacitor. The carriage cost me more
than the parts. You need to be a techie to dismantle and replace the
parts. There are online manuals and repair instructions, but you
need to be familiar with desoldering components.

To replace assemblies, both the AC power supply and the fuser
are on four screws, though you need to take the cover off.
I'd guess that your fuser is producing some heat, as the machine
should give a fault indication if it doesn't see the fuser heating up
at all. Old age can cause the pins of the modules to freeze in
place and it may require more major dismantling to free them
up. Excessive force is contra indicated.
Click to expand...

OK, thanks...that provides significant additional info...

Yes, it is the Canon SX...it isn't actually the HP LJ II, it's a QMS
PS810, but physically the two are virtually idential--only a minor
difference in the control panel and the QMS firmware/PS engine. I used
the LJ as QMS being relatively rare, figured good chance would get no
response to it if mentioned it specifically...

I'm moderately capable, have eng'g degree which as my tech of manyu
years (and many others I've known as well) said only made us
collectively more dangerous than we otherwise would have been... :)
 
Since you're not getting any sort of error message (Error 50, etc.), then I'd
guess that the rollers in the fusing assembly have deteriorated to the point
they're not squeezing the toner into the paper sufficiently. Time for a new
SX engine fusing assembly.
 
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