Thermostat for laser printer fuser temp?

[Lionel]

I am *guessing* that the E150 indicates the temperature.
Take a look at Mouser part # 802-STO-160 to see if
it will work for you. It is normally closed, and
opens when the emperature rises above 155 to 165 F

The temperature is rated in degrees C, not F, but other than that, it
looks like you have the righ part.

 

[Lionel]

Lionel sez:


I found most of what you say to be so.

<grin> I learned all that when I worked for Canon (who make the laser
engines used in most of the big brandname printers). I used to rebuild
& recondition about half a dozen fuser assemblies a week, so I still
remember most of the details.

I disassembled the "fuse" and it turns out to be a single pair of contacts
with a bi-metallic dome (think kid's "cricket" sound toy that you pressed
with your thumb) that opens the contacts. When it cools, the contacts are
supposed to close again. Mine didn't seem to do that.

You're right: there was a buildup of gunk (toner) under the thin teflon (or
whatever) strip that separated the thermistor from the roller. Cleaned that
up with a blast of canned air. Luckily it wasn't sticky at all.

I put the thermal switch back together and installed it All seems to work OK
but I won't put the printer into service until I replace the switch.

Where would you look for one?

Good question. When I worked for Canon, we just ordered them from the
spare parts department, but you should be able to find them at laser
spare parts companies that cater for (any of) HP, Apple, Brother &
Canon laser printers.
On the part itself, you should be able to find a Canon part number,
which would be formatted something like: "RG?-????-???". Googling for
that part number (leave off the last '-???' part) should turn up
something. Don't pay more than $10.
Per Ed's earlier post, this looks like a suitable substitute:
<http://www.mouser.com/search/refine.aspx?Ntt=802-STO-325>

(It's a shame I tossed my laser printer junk box the last time I moved
house, or I could probably could've given you one.)

Make sure you're very careful about comparing the replacement part to
the original, & in how you mount it. If the original had yellow/orange
film (anti-stick) over it, you'll need to come up with some way of
mounting the new thermoswicth so that it doesn't rub on the roller, or
it'll scrape off the teflon coating, which will leave streaks on your
printouts. The standard method is to bend the mounting bars on the
thermoswitch so that it doesn't quite touch the roller.

Thanks.

My pleasure, I'm glad I could help.

 

[Lionel]

ehsjr sez:


Thanks for your comments, Ed. I saw that one but would like to find a direct
replacement without having to hack off tabs, etc (original has no separate
mounting tabs; the connection tabs are use for screw mounting also).

It should be okay to snip off the mounting tabs with tinsnips or
whatever.

Also, fuser assembly gets up to high 300f+ so I, too, am guessing at the temp
rating. 150f seems a bit low for being in such proximity to the headed roller
(few tenths of an inch). Maybe it's 150c (302f)? It *is* a Japanese
printer...

That's correct, the original part is rated at 150c.

The nearest Stancor product is 157f (315c)...

You mean 315F/157c.

too high?

No, that should be correct. The thermoswitch is intended to trip if
the temperature exceeds the working temperature. The original part
specifies the working temperature, but the Stancor part specifies the
trip temperature.

 

[Lionel]

Usually these discount printers come with a toner cartridge that is
about half full so you will be buying toner pretty soon anyway.
Sometimes I believe they sell printers below cost just to create a
market for toner. I am sure that is true for ink jets

That's exactly what they do.

 

[Lionel]

Anybody know how do dial down the toner use on this printer?

It depends very much on the engine model. Look for a green plastic
dial somewhere in the guts (EHT controller assembly, specifically) of
the printer. It should be visible with the lid open, but without
needing to remove any screws. If your printer has an LCD on the
control panel, there should also be a density setting somewhere in the
configuration menu.
OTOH, see below:

The white space
on the pages seems to be a bit gray, and the build-up of toner under the
thermistor also suggests a slightly "rich mixture".

Is the grey on the blank areas consistant in density, or does it
contain very faint ghost images of the previous page? If the latter,
you have a problem with the drum-cleaning system, which is often due
to a bad cartridge. If you're getting streaks down the page, you
likely have dirty corona (high voltage) wires, that're preventing the
drum from getting an even charge across its full width. Another
possibity is dirt/dust bunnies in the window between the
laser-scanning unit & the slot on the top of the toner cartridge. It's
safe to dust out the window & mirror with a clean, dry paintbrush.

If it was easy to remove the controller board (or just have access to it) I'd
probably do a little exploring. But the pan that holds the controller PCB is
basically the frame for all the plastic bits to bolt to. It's akin to the
heater core in a car. It is suspected that the heater core is the first part
placed on the assembly line, and the rest of the car is built around it.

That's not the part you need to be looking at anyway. (And on the
bigger laser engines, you access the controller boards from underneath
the printer, not from the top.)

 

[Jim Thompson]

[snip]

"Some people are alive only because it is illegal to kill them."

Leftist weenies are alive only because it is illegal to kill them ;-)

...Jim Thompson

 

[Ecnerwal]

Usually these discount printers come with a toner cartridge that is
about half full so you will be buying toner pretty soon anyway.
Sometimes I believe they sell printers below cost just to create a
market for toner. I am sure that is true for ink jets

It's not only true, they also have a separate "drum cartridge" (rather
than the old system of toner and drum as one). This would be fine,
except that the pricing there is literally insane: I recently purchased
two complete printers, because the price of the complete printer with
drum cartridge and half-full toner cartridge was _less_ than the drum
cartridge alone. I have two complete chassis for spare parts and/or the
junkyard...I'd offer to send the OP a thermostat, but it's clearly a
different printer (this one reads the hot roller) and there are no
visible markings on it at all (I have not fully disassembled the fuser
assembly to see if there are any on the backside of it, but the visible
parts have no markings).

Brother, at least, has also been working to reduce the capacity of their
toners and drums - the 51XX series costs significantly less per page
than the newer 20XX series. Both have the nasty and undesirable behavior
of simply stopping printing when THEY think the toner is low, or the
drum is shot (as does the newer HP we have) rather than advising you
that the toner is low and continuing to print until you don't like the
prints (more evidence that it's all a scam to sell more toner).

It gets worse with color laser printers. Saw one on sale recently for
$300, priced a set of toner, $600, drum was another $200-300...and the
"starter toner", upon investigation, was not even half-full - more like
10%.

 

[Lionel]

[snip]

"Some people are alive only because it is illegal to kill them."

Leftist weenies are alive only because it is illegal to kill them ;-)

Mate, if it were legal to kill right-wing weinies, I'd have a /lot/ of
notches on my weapon-of-choice.

 

[SparkyGuy]

Make sure you're very careful about comparing the replacement part to

the original, & in how you mount it. If the original had yellow/orange
film (anti-stick) over it, you'll need to come up with some way of
mounting the new thermoswicth so that it doesn't rub on the roller, or
it'll scrape off the teflon coating, which will leave streaks on your
printouts.

It seems that the thermo shut-off is positioned in close proximity to -- but
not touching -- the heated roller. It's designed to open when the temperature
(within about 1/8 inch of the roller) reaches 150c.

The standard method is to bend the mounting bars on the
thermoswitch so that it doesn't quite touch the roller.

Yeah, that's how it is in this one.

Thanks.

 

[Lionel]

It seems that the thermo shut-off is positioned in close proximity to -- but
not touching -- the heated roller. It's designed to open when the temperature
(within about 1/8 inch of the roller) reaches 150c.

Close, but not quite correct. It's designed for a hot roller operating
temperature of 150c, & opens if it goes significantly higher than
that.

Yeah, that's how it is in this one.

Good. That version of the design is easier to fix than the version
where the thermal cutout touches the roller, which used a special
cutout that had an indentation in it that matched the shape of the
roller. (We fixed the older version by bending the tabs on a standard
cutout so that they match the roller distance of the newer type.)

Thanks.

My pleasure. It's nice to know that my hard-earned experience with
laser engines isn't just wasting space in my brain. ;^)

 

[ehsjr]

The temperature is rated in degrees C, not F, but other than that, it
looks like you have the righ part.

Mouser gives the ratings in both F and C. If he needs 150 C
then the part I posted is wrong. The closest part # would be
802-ST0-335 which is rated 315-335 F, 157-169 C

Ed

 

[Lionel]

Mouser gives the ratings in both F and C. If he needs 150 C
then the part I posted is wrong. The closest part # would be
802-ST0-335 which is rated 315-335 F, 157-169 C

Yep, that's the one I suggested after reading your post.

 

[ehsjr]

Close, but not quite correct. It's designed for a hot roller operating
temperature of 150c, & opens if it goes significantly higher than
that.




Good. That version of the design is easier to fix than the version
where the thermal cutout touches the roller, which used a special
cutout that had an indentation in it that matched the shape of the
roller. (We fixed the older version by bending the tabs on a standard
cutout so that they match the roller distance of the newer type.)




My pleasure. It's nice to know that my hard-earned experience with
laser engines isn't just wasting space in my brain. ;^)

Not wasted - it is very interesting! I take it that
most of the time this type of failure is caused by
the build up of crud in there? Is it a fool's errand
to try to do preventive maintenance - maybe just as
likely to cause a problem as to prevent it? Also,
when these printers start "smudging" the non-printed
area, is that a sign of impending toner replacement?
The prior printer did that for a long while before
the printing became light & toner needed replacement.
I tried to clean it on a number of occasions, but was
not successful in clearing the problem. So either
I wasn't cleaning the right things, or it wasn't an
issue of cleaning.

Ed

 

[ehsjr]

Yep, that's the one I suggested after reading your post.

Thanks! Glad you picked up on the error. It would be a bummer
if he put in the wrong part, to say the least. And I've enjoyed
reading & learning from your posts on this.

Ed

 

[Lionel]

Not wasted - it is very interesting!

Thanks.

I take it that
most of the time this type of failure is caused by
the build up of crud in there? Is it a fool's errand
to try to do preventive maintenance - maybe just as
likely to cause a problem as to prevent it?

Not if you know what you're doing, but it's enough of a pain to get at
the relevant part of the fuser that I've never bothered doing it
unless I run into symptoms like the OP's, or am opening up the printer
for some other reason, in which case I'll give it a clean up while I'm
in there.
BTW, a tiny squirt of silicon spray on the woolly, removable wiper on
top of the hot roller for every ream of paper you put through the
printer will greatly extend the life of the teflon coating on the hot
roller, which is hard to obtain, & a pain to replace. It's also good
to clean the accumulated gunk of the separation claws (that 'scrape'
the paper off the hot roller in its way out), because they're prone to
causing paper jams on exit, & can scratch gouges in the teflon
hot-roller coating.

Also,
when these printers start "smudging" the non-printed
area, is that a sign of impending toner replacement?

It totally depends on the cause, of which there several for that
particular symptom. (And there are unrelated problems that cause
symptoms that look very similar to the inexperienced.) But yes, the
most common cause of dirty backgrounds is a cartridge on its last
legs. At a site where they have more than one printer of the same
type, the easiest, quickest way to detect a bad cartridge is to swap
cartridges with another unit, then do a test print from both.

The prior printer did that for a long while before
the printing became light & toner needed replacement.
I tried to clean it on a number of occasions, but was
not successful in clearing the problem. So either
I wasn't cleaning the right things, or it wasn't an
issue of cleaning.

Most likely the latter. If it came good when you put in the new
cartridge, you've got the answer to your question.

 

[Lionel]

Thanks! Glad you picked up on the error. It would be a bummer
if he put in the wrong part, to say the least. And I've enjoyed
reading & learning from your posts on this.

Thanks again. It's always nice when one's advice is appreciated.

 

[SparkyGuy]

I'd offer to send the OP a thermostat, but it's clearly a

different printer (this one reads the hot roller)

I was mistaken -- the thermal cut-out safety switch in the Samsung 4100 I'm
trying to fix does monitor thet hot roller (I always though the red-coated
one was the hot one... apparently not).

and there are no
visible markings on it at all (I have not fully disassembled the fuser
assembly to see if there are any on the backside of it, but the visible
parts have no markings)

Well if it looks like this:

<http://img12.picsplace.to/img.php?file=img12/1/Thermo.jpg>

(the black end of it with the two mounting/electrical tabs is visible from
the exterior of the fuser) please consider it.

Thanks,
Sparky

 

[ehsjr]

Thanks.




Not if you know what you're doing, but it's enough of a pain to get at
the relevant part of the fuser that I've never bothered doing it
unless I run into symptoms like the OP's, or am opening up the printer
for some other reason, in which case I'll give it a clean up while I'm
in there.
BTW, a tiny squirt of silicon spray on the woolly, removable wiper on
top of the hot roller for every ream of paper you put through the
printer will greatly extend the life of the teflon coating on the hot
roller, which is hard to obtain, & a pain to replace. It's also good
to clean the accumulated gunk of the separation claws (that 'scrape'
the paper off the hot roller in its way out), because they're prone to
causing paper jams on exit, & can scratch gouges in the teflon
hot-roller coating.




It totally depends on the cause, of which there several for that
particular symptom. (And there are unrelated problems that cause
symptoms that look very similar to the inexperienced.) But yes, the
most common cause of dirty backgrounds is a cartridge on its last
legs. At a site where they have more than one printer of the same
type, the easiest, quickest way to detect a bad cartridge is to swap
cartridges with another unit, then do a test print from both.




Most likely the latter. If it came good when you put in the new
cartridge, you've got the answer to your question.

Lionel,

Thanks. Good info, as usual!

Ed

 

[Guest]

just gotta love the tricks these marketing moguls use to extract our money
from our wallets.

they are not concerened with conservation, re-use or longevity. they only
seek to enrich themselves by selling us time limited and sales strategic
devices that require extreme cost to service or replenish. the initial
purchase is a come-on

the HP deskjet cartridge, (yes that tiny little ink thing) has probably
generated more profit for HP than most all its gear combined.

no one in business for profit ever cares about resource depletion until
their own kids die from it.. & even then, they figure they will leave THAT
problem for their kids to solve. "if it aint broke,doan figz it"

 

[Lostgallifreyan]

no one in business for profit ever cares about resource depletion
until their own kids die from it.. & even then, they figure they will
leave THAT problem for their kids to solve. "if it aint broke,doan
figz it"

Don't kid yourself. They don't think of it AT ALL. Period. There are two
ways to think things like this, unless you're no longer sane, in which case
all bets are off:
1. You assume it IS relevent to you, and all that you care about, in which
case it nags at you till you eventually do something, ANYTHING, to appease
the nagging sense of doubt, in order to make yourself feel more secure. OR
2. You assume your security is ALREADY assured, thus you don't think of
doing anything to change what others appear to be whinging about as a
perceived threat.

Given that the firms doing this ARE amongst the most secure, financially,
politically, and socially, their arrogance is the cause. This is not mere
ignorance, it is WILLFUL ignorance, the worst and most dangerous kind. It
also the kind that is hardest to forgive, and if resources become low
enough to make a majority of people start to begrudge this and DO something
about the way they choose to spend their money, it will carry on. There are
firms that will sell cheap refills, but these aren't the cure, they DEPEND
on the problem to exist.

Now, as I'm saying my small rant in the presence of electronics engineers,
some of which are considering their own business management as well as
electronics details, I won't try to tell them solutions they probably know
more about themselves, it's enough to point out tht there will be a market
for products that don't fleece the buying public at unacceptable expense.

I do have one small suggestion, I guess. Innovation is the ONLY way a small
firm can get ahead. After all, it;s buying up innovators that makes the big
firms get ahead, right? So, if small firms patent their stuff precisely
instead of in the aggressive way large firms do to try to stop others,
instead of just protecting themselves, this can help, it can prevent a
large firm from muying and burying innovation that threatens their own
wasteful empires, and it can also prevent them from revising history to try
to force their exploitation of your ideas. Patent it under your own name if
you invent it. A firm can't claim your idea even if you thought it up on
their time! Do they OWN your mind? I think not. At least copyright it by
sending yourself signed sealed copies. Do this before it becomes valuable
to someone else.

There may be all kinds of better ideas to erode the tech society that
wastes so heavily, but I'm not inside it enough to think of much more than
I have said here.