Thermostat for laser printer fuser temp?

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"

direct
separate
temp
roller
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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.
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Yes. Help each other!

No, actually they simply use it to amuse themselves until the Messiah comes (c: I mean, find something you enjoy doing and do it!
And lighten up! FBt
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wrote:

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

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

You mean 315F/157c. ;)

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.
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wrote:

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

Leftist weenies are alive only because it is illegal to kill them ;-)
...Jim Thompson
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| Analog Innovations, Inc. | et |
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On Thu, 08 Mar 2007 18:20:58 -0700, Jim Thompson

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

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
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wrote:

Yep, that's the one I suggested after reading your post. ;)
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Lionel wrote:

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
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wrote:

Thanks again. It's always nice when one's advice is appreciated. ;)
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If you are in the US or Canada call Premier Parts - Phone: 800-668-8778 or Fax: 800-668-8037
They are the Samsung dealer. The rating for the thermo-fuse is rated in Celius so it is 150C. I've got quite a few Samsung printers I use for parts so I'll look and see if I have a fuser or the thermister/thermo-fuse.
SparkyGuy wrote:

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wrote:

150c thermal safety fuse. They're usually a single-shot unit, like a normal fuse, & must be replaced if they fail. If it fails, you need to find out why the fusing assembly is overheating in the first place. The most common cause is gunk building up on the thermistor used to sense the temperature on the hot roller. Look for a thin cable running to a small module pressed against the hot roller, situated under a cover. The module will have a heat-proof, non-stick film over it that is probably covered in cooked toner/dust. The film is quite easy to tear/cut, so scrape off the gunk with omething wooden or plastic. Before reassembling, make sure that the module is pressing firmly against the hot roller. It's also a good idea to check that the thermister is working correctly: connect an ohmmeter across the connector & verify that the resistance changes when you heat the module with hair-dryer. Alternatively, press the sensor against a cup of boiling water. Do not try to test the thermistor with a flame or soldering iron, or you will likely damage the internal connections.
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Lionel sez:

I found most of what you say to be so.
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?
Thanks.
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Anybody know how do dial down the toner use on this printer? 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".
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.
Thanks.
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wrote:

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:

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.

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.)
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wrote:

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. ;)

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 2-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.

My pleasure, I'm glad I could help.
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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.

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

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. ;^)
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Lionel wrote:

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
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