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Re: [Electronics_101] SUNBEAM ELECTRIC BLANKET

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  • jong kung
    dave,   ... Anybody have any ideas on what would cause the controller to go ... shortly after it is turned on. Supposedly the circuit ... the problem, but
    Message 1 of 9 , Jan 3, 2010
      dave,







       









      Anybody
      have any ideas on what would cause the controller to go
      > into fault mode
      shortly after it is turned on. Supposedly the circuit
      > in the blanket is
      the problem, but what component?


      These are really vague description of your problem.  Have you tried to open the controller to see if there's anything obviously wrong?  In any diagnostics the first part is a good ONCE OVER to find any obvious problem.  That also include sight, odor, sound, heat, etc..

      Do you see anything out of place?
      Does it smell funny (burning)?
      Does it click or hum or buzz (or any other sound coming from it)?
      Does it feel warm / hot to the touch?

      Any other observation?

      ====

      Do you have a multimeter / voltmeter that we can direct you to use for checking things out?  It would be nice if you check the OHM reading of the blanket to see if the heating wiring isn't broken.

      ====

      If I'm not mistaken, these things are VERY simple with bi-metal switch for thermostat and just straight mains power through the blanket.  Recently I've seen (in advertisement) a low voltage (20v) blanket, but I think these are the exception.  So whatever problem you have, it should be something that is burnt out, wires broken, etc.


      Jong



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      [Non-text portions of this message have been removed]
    • Stefan Trethan
      The new ones have a thermistor wire all the way parallel to the heater. This is to avoid local hotspots that the thermostat wouldn t catch. Electric blankets
      Message 2 of 9 , Jan 3, 2010
        The new ones have a thermistor wire all the way parallel to the
        heater. This is to avoid local hotspots that the thermostat wouldn't
        catch. Electric blankets were the major source of electrically caused
        hause fires some years ago, if I recall right. Definitely no bypassing
        any safety features here!

        There also seems to be some permanent (trip once and throw away)
        overheating protection, at least the manual says so, but I have no
        idea how it's implemented.

        ST

        On Sun, Jan 3, 2010 at 10:26 AM, jong kung <jongkung01@...> wrote:

        > If I'm not mistaken, these things are VERY simple with bi-metal switch for thermostat and just straight mains power through the blanket.  Recently I've seen (in advertisement) a low voltage (20v) blanket, but I think these are the exception.  So whatever problem you have, it should be something that is burnt out, wires broken, etc.
        >
        >
        > Jong
      • Sheldon Dedek
        My blanket goes into fault mode (Sunbeam as well, but is heated matress pad), blinky blinky light on controller. I discovered that the plug sometimes comes
        Message 3 of 9 , Jan 3, 2010
          My blanket goes into fault mode (Sunbeam as well, but is heated matress
          pad), blinky blinky light on controller. I discovered that the plug
          sometimes comes loose during the night. Just plugging back in doesn't
          fix it, you have to unplug the controller's AC cord from the wall as well.

          That being said, take a hard look at the contacts on both the blanket
          and controller side of the connector. All of the contacts are all equal
          distance inside each half of the connector.

          I don't know about a sensing element in the pad / blanket itself though.
          My pad has a 4 wire connector, and 2 controllers (queen size). I am
          75% certain that mine likely uses PWM to control the amount of heat
          being put into the blanket. Older blankets / pads used a bimetallic
          strip in the controller itself. I could hear mind click on and off
          during the night. Drove me nuts.

          Good luck with yours. Wrong time of season to lose the prewarming
          option on the bed!

          Sheldon
        • dave
          Thanks to all who responded. Here is more information on the blanket. The circuit in the blanket consists of a heating element, that is like a lamp cord with
          Message 4 of 9 , Jan 5, 2010
            Thanks to all who responded.
            Here is more information on the blanket.
            The circuit in the blanket consists of a heating element, that is like a lamp cord with 25 ohm conductors and 500 ohms between conductors, three surface mount resistors and a PNP transistor.

            ONE PNP PNP 22OOPF
            AC--<<---HEATING---EMITTER---COLLECTOR---22K-->>--IN CONTROLLER---AC
            INPUT ELEMENT ^ OHM 330K OHM INPUT
            NEUTRAL 1.5K OHM HIGH
            ^ PNP OTHER ^
            BASE---62K OHM---HEATING->>--FUSE--TRIAC-^
            ELEMENT IN CONTROLLER

            I found the problem to be intermittent metalization on one end of a resistor. I replaced the resistor.

            The blanket now works in this manner.
            When it is first turned on the power to the heating element is a half-wave, then after about 20 seconds it switches to full-wave, after that its full-wave on or off zero crossing switching, no PWM. When "on" the voltage across each heating element is approximately 6 volts full wave AC.
            Dave
          • joesmith@cvctx.com
            Any idea where this thermisistor is located? Thanks Joe in Texas(West Point,Monitor Repair) Quoting Stefan Trethan : The new ones have a thermistor wire all
            Message 5 of 9 , Jan 6, 2010
              Any idea where this thermisistor is located?

              Thanks

              Joe in Texas(West Point,Monitor Repair)

              Quoting Stefan Trethan :

              The new ones have a thermistor wire all the way parallel to the
              heater. This is to avoid local hotspots that the thermostat wouldn't
              catch. Electric blankets were the major source of electrically caused
              hause fires some years ago, if I recall right. Definitely no bypassing
              any safety features here!

              There also seems to be some permanent (trip once and throw away)
              overheating protection, at least the manual says so, but I have no
              idea how it's implemented.

              ST

              On Sun, Jan 3, 2010 at 10:26 AM, jong kung wrote:

              > If I'm not mistaken, these things are VERY simple with bi-metal
              > switch for thermostat and just straight mains power through the
              > blanket. Recently I've seen (in advertisement) a low voltage (20v)
              > blanket, but I think these are the exception. So whatever problem
              > you have, it should be something that is burnt out, wires broken, etc.
              >
              >
              > Jong





              [Non-text portions of this message have been removed]
            • joesmith@cvctx.com
              Thanks,printed and filed. Joe Smith West Point Monitor Repair West Point,Texas 78963-5022 Quoting dave : Thanks to all who responded. Here is more information
              Message 6 of 9 , Jan 6, 2010
                Thanks,printed and filed.

                Joe Smith

                West Point Monitor Repair

                West Point,Texas

                78963-5022

                Quoting dave :

                Thanks to all who responded.
                Here is more information on the blanket.
                The circuit in the blanket consists of a heating element, that is like
                a lamp cord with 25 ohm conductors and 500 ohms between conductors,
                three surface mount resistors and a PNP transistor.

                ONE PNP PNP 22OOPF
                AC----IN CONTROLLER---AC
                INPUT ELEMENT ^ OHM 330K OHM INPUT
                NEUTRAL 1.5K OHM HIGH
                ^ PNP OTHER ^
                BASE---62K OHM---HEATING->>--FUSE--TRIAC-^
                ELEMENT IN CONTROLLER

                I found the problem to be intermittent metalization on one end of a
                resistor. I replaced the resistor.

                The blanket now works in this manner.
                When it is first turned on the power to the heating element is a
                half-wave, then after about 20 seconds it switches to full-wave, after
                that its full-wave on or off zero crossing switching, no PWM. When "on"
                the voltage across each heating element is approximately 6 volts full
                wave AC.
                Dave





                [Non-text portions of this message have been removed]
              • Stefan Trethan
                I think inside the blanket. The user manual and 4 plug connector made me assume there is a NTC or PTC wire strung out alongside the heating element. This is
                Message 7 of 9 , Jan 7, 2010
                  I think inside the blanket. The user manual and 4 plug connector made
                  me assume there is a NTC or PTC wire strung out alongside the heating
                  element.

                  This is just a theroy. I'm not gonna take it apart just yet, my sewing
                  isn't so good ;-)


                  ST

                  On Thu, Jan 7, 2010 at 1:57 AM, <joesmith@...> wrote:
                  >
                  >
                  >   Any idea where this thermisistor is located?
                  >
                  >   Thanks
                  >
                  >   Joe in Texas(West Point,Monitor Repair)
                  >
                • joesmith@cvctx.com
                  Sounds good to me,we have 2 king size(Guest apt upstairs),so they aint cheap,That s for sure. If I get there before you do then I will post it here. Thanks
                  Message 8 of 9 , Jan 7, 2010
                    Sounds good to me,we have 2 king size(Guest apt upstairs),so they
                    aint cheap,That's for sure.

                    If I get there before you do then I will post it here.

                    Thanks Again,Stefan,Please pardon my curosity

                    ,,,errrrrr,where IS gmx@ located on the globe.

                    Quoting Stefan Trethan :

                    I think inside the blanket. The user manual and 4 plug connector made
                    me assume there is a NTC or PTC wire strung out alongside the heating
                    element.

                    This is just a theroy. I'm not gonna take it apart just yet, my sewing
                    isn't so good ;-)

                    ST

                    On Thu, Jan 7, 2010 at 1:57 AM, wrote:
                    >
                    >
                    > Any idea where this thermisistor is located?
                    >
                    > Thanks
                    >
                    > Joe in Texas(West Point,Monitor Repair)
                    >





                    [Non-text portions of this message have been removed]
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