Thermostat for laser printer fuser temp?

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

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. ;)

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:

(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.

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.

That's exactly what they do.

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.)

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

...Jim Thompson

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

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

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.

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. ;^)

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

Ed

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

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

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

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. ;)

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

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).

Well if it looks like this:

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

Thanks, Sparky

Lionel,

Thanks. Good info, as usual!

Ed

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"