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Thermostat for laser printer fuser temp?

Discussion in 'Electronic Components' started by SparkyGuy, Mar 7, 2007.

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  1. SparkyGuy

    SparkyGuy Guest

    Fuser quit working on my laser printer. Removed the fuser and found that the
    snap-action bimetallic thermostatic switch for the fuser heating element is
    open-circuit. I removed it from the fuser and pried it open. Looks brand new.
    Reassembled it and it now conducts. Then it opened again. Not reliable enough
    to reinstall due to critical job it does. It rides against the cool roller
    (not the heated one) and cycles the heating element so as to keep the
    temperature constant.

    Markings on front:

    on rear:

    I've googled but only find these in Eastern Europe or China.

    Any local suppliers?

    Replacement part not available from mfr., and replacement fuser assembly is
    not financially viable; it'll cost as much as I paid for the printer.

  2. N Cook

    N Cook Guest

    Are U sure? You could only indirectly control the fuser temp. if there was a
    continuous, unvarying , throughput of paper, no stopping and starting.
    Is it not just a general output , via air environment, over-temperature cut
    out ?
  3. PeterD

    PeterD Guest

    Make and model of hte printer, please.
  4. SparkyGuy

    SparkyGuy Guest

    Make and model of hte printer, please.

    Samsung SCX-4100

  5. SparkyGuy

    SparkyGuy Guest

    Are U sure? You could only indirectly control the fuser temp. if there was a
    You're probably right. Now that I look at the fuser in the daylight (not in
    early hours of the morning) I see that there is what must be a small
    thermistor resting on the heated roller. *This* is most likely the feedback
    for the heater circuit.

    The bimetallic switch must be a over-temp circuit breaker, as you say.

    And I now see that they both come in contact with the heated roller, not the
    pinch roller (I thought the red roller was high-temp stuff...)

    But as for replacement, it's all moot, yes? Or do you have a suggestion re. a

  6. Guest

  7. ehsjr

    ehsjr Guest

    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

  8. SparkyGuy

    SparkyGuy Guest

    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).

    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

    The nearest Stancor product is 157f (315c)... too high?
  9. SparkyGuy

    SparkyGuy Guest

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

    Er... 157c (315f).
  10. ehsjr

    ehsjr Guest

    I dunno - but I can commiserate with your situation.
    When my toner ran low, I went to Staples to buy a
    replacement. 70 dollars! But, serendipity - they had
    an entire printer (Brother HL-2040) on sale for $110,
    and it's faster and better than the old one. (The price
    has dropped on them since I bought, so they are now
    $120 not on sale.) Anyway, it worked out well for me,
    but $70 for the toner still rankles! Interesting
    psychology - I didn't spend $70 and if I had I'd
    still be unhappy about it. I spent $110 - $40 more,
    and I'm pleased as punch. And it's actually more than
    $40 extra when you add in the tax.

    Maybe the people who set the prices have an ulterior
    motive? (How do you make a "frowny face" icon with
    smoke coming out of its ears?)

  11. SparkyGuy

    SparkyGuy Guest

    I dunno - but I can commiserate with your situation.
    Yeah, just now I looked on Office Depot for toner and it's $85!! And it's a
    *tiny* cartridge. Will see what's on sale when this toner runs out (c:

    But what kind of world are we making where the economy pushes us to fill
    landfills with this stuff? Maybe total recycle (what with RoHS regulation)
    every time toner runs out? Hmm... Are disposable computers (with removable
    data cartridge) next? Cars?
  12. cr500r

    cr500r Guest

    I use to get toner for about $32 instead of staples
    $80 or so, and it works good.
    I won't buy a laser printer without checking to make sure I can get the
    toner cheap online somewhere :)
  13. C

    C Guest

    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.
  14. Guest

    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
  15. Lionel

    Lionel Guest

    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.
  16. SparkyGuy

    SparkyGuy Guest

    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?

  17. SparkyGuy

    SparkyGuy Guest

    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.

  18. Clint Sharp

    Clint Sharp Guest

    ISTR reading somewhere that Xerox's business plan is to sell consumables
    and the hardware is only sold to create the market. Xerox used to give
    free printers to companies if they signed up to a contract for
    consumables. If toner and ink wasn't so profitable why would
    manufacturers go to lengths to prevent people cloning or refilling
  19. PeterD

    PeterD Guest

    Kodak marketing: give away the camera and sell the film...

    Worked well until there was no film!
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