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Finding datasheet for a chip

Discussion in 'Electronic Repair' started by D, Feb 6, 2012.

  1. D

    D Guest

    I recently bought a heating pad which has a "feature" which shuts the
    heat off after 2 hours. Virtually all pads seem to be made this way now,
    unfortunately. I would like to defeat this. I can probably jumper
    around the timer control portion of the switch to accomplish this, but I
    see in doing some searching that on at least one older model, some
    modification of the circuitry around the chip can accomplish this, too
    http://www.ralree.com/2007/12/13/disabling-auto-off-on-the-sunbeam-health-at-home-heating-pad/
    Unfortunately, the circuit on that pad is not the same as mine, which
    is centered around an 8 pin chip marked "SEDS 13-000022 R1017A" I can't
    seem to find any data on this chip. Tried www.alldatasheet.com, no info
    that I could find. Anyone know where I might look, or have any other
    ideas for eliminating the timed off action?

    TIA

    Dan
     
  2. Rich Webb

    Rich Webb Guest

    A 555 timer chip is only eight pins but so are many smaller
    microcontrollers. Can you take a picture of the circuit board (both
    sides, perhaps) and upload that to Flickr, ImageShack, or similar? That
    might help narrow down the choices somewhat.
     
  3. Rich Webb

    Rich Webb Guest

    True but it's most likely going to be a counter like the other examples
    or, perhaps, something more modern like the aforementioned uC with an
    internal RC oscillator. Could be a 4-banger, even. But looking at where
    it is in the layout can give some clues to getting the OP a way to
    accomplish his intent.
     
  4. D

    D Guest


    Thanks for the great replies. I'm not sure what the chip is, it's a
    SOP8 package, not a DIP like a 555 timer. Probably right, some
    proprietary design with little data available. One side of the line is
    switched via a small transistor, I disconnected the transistor & ran
    that side of the line directly. Heat levels are adjusted with the
    control switch on the other side of the line. So far so good. Also,
    the bloody thing is SUPPOSED to shut off at 2 hours, and it's barely
    making it past ONE. PITA.

    Dan
     
  5. D

    D Guest

    I just re-read this & want to clarify that the pad IS now staying "on",
    after the mods. The message above may not have been clear. Thanks again.

    Dan
     
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