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Troubleshooting Electric Blanket

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    #21
    Re: Troubleshooting Electric Blanket

    check resistance of the element ... i guess it will be about same as a 60w to 100w light bulb .

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      #22
      Re: Troubleshooting Electric Blanket

      Mind explaining in baby terminology, what you're referring to when saying "element"?

      EDIT: At this stage I am not even connecting the actual blanket, the controller should light an LED if it's functioning (I also know cause I have a very similar one that works, LED lights on even with the blanket disconnected).

      Originally posted by petehall347 View Post
      check resistance of the element ... i guess it will be about same as a 60w to 100w light bulb .
      Last edited by DanFen; 04-04-2020, 02:02 PM.

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        #23
        Re: Troubleshooting Electric Blanket

        There are two switch contacts, one on the line side one on the neutral side, They both need to be making contact, There must be a plastic actuator that presses them so they make contact. I would be carefull there will be 240vac across them.

        I also just notice a smd resistor that seems to be missing, It is R2, it is part of a series of 4 resistors
        Last edited by R_J; 04-04-2020, 02:34 PM.

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          #24
          Re: Troubleshooting Electric Blanket

          Are you referring to these two?

          Originally posted by R_J View Post
          There are two switch contacts, one on the line side one on the neutral side, They both need to be making contact, There must be a plastic actuator that presses them so they make contact. I would be carefull there will be 240vac across them.
          Attached Files

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            #25
            Re: Troubleshooting Electric Blanket

            Yes I am, I also mentioned a missing R2 resistor, it likely fell off at one time and is missng which is likely causing the problem. It seems to be for the low voltage that supplies the ic. Check if it is still in the case or on the surface where you opened the case.

            This is why it's not working, R2 is part of the 4 resistors that drops the ac voltage that feeds D1, which is then clamped to around +5v by ZD1 (N8). That feeds D2 and capacitor C1
            Attached Files
            Last edited by R_J; 04-04-2020, 02:46 PM.

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              #26
              Re: Troubleshooting Electric Blanket

              Yeah I'm extra careful with that 240V thanks for the reminder

              To be honest, those contacts seem to be making contact already, and there's no device that pushes them. Not sure what the idea behind it is. Tried to take a photo using a magnifying lens.

              Now I see the missing resistor. I'll try to find an equivalent one from a laptop/computer motherboard. Should have done a better visual inspection! You've got a good eye

              Originally posted by R_J View Post
              Yes I am, I also mentioned a missing R2 resistor, it likely fell off at one time and is missng which may be causing the problem
              Attached Files

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                #27
                Re: Troubleshooting Electric Blanket

                R2 should be a 1002 (10K) The contacts could be making connection now, but I suspect there is a slide (power on/off) or something in the case that causes them to open.

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                  #28
                  Re: Troubleshooting Electric Blanket

                  Yes found the mechanism, when it's 0 it moves a plastic underneath them and stops the contact. Thanks for the explanation

                  Hope I'll find a 1002!

                  Originally posted by R_J View Post
                  R2 should be a 1002 (10K) The contacts could be making connection now, but I suspect there is a slide (power on/off) or something in the case that causes them to open.

                  Comment


                    #29
                    Re: Troubleshooting Electric Blanket

                    My luck says not today, I couldn't find any 1002 resistors on any PC/Laptop board.

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                      #30
                      Re: Troubleshooting Electric Blanket

                      look for a couple 5k and put them in series, it does'nt need to be exact, as long as it is close to 10k, 15k would likely work as well.

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                        #31
                        Re: Troubleshooting Electric Blanket

                        Would 103 work? It's 10k, but smaller in size.

                        Originally posted by R_J View Post
                        look for a couple 5k and put them in series, it does'nt need to be exact, as long as it is close to 10k, 15k would likely work as well.

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                          #32
                          Re: Troubleshooting Electric Blanket

                          It should work to test, I would try and find the correct type. The original must have fallen out at one time, too bad it was'nt still in the case.

                          Comment


                            #33
                            Re: Troubleshooting Electric Blanket

                            I can order a batch of 100 for 81 euro cents from Aliexpress. It's just a matter of waiting and having 99 other resistors sitting there.

                            Originally posted by R_J View Post
                            It should work to test, I would try and find the correct type. The original must have fallen out at one time, too bad it was'nt still in the case.

                            Comment


                              #34
                              Re: Troubleshooting Electric Blanket

                              The 103 will likely be ok, but being smaller the wattage is likely lower so it could just open up after a while.

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                                #35
                                Re: Troubleshooting Electric Blanket

                                Thanks for your help I'll just place the order and then update this thread when it's installed.

                                Originally posted by R_J View Post
                                The 103 will likely be ok, but being smaller the wattage is likely lower so it could just open up after a while.

                                Comment


                                  #36
                                  Re: Troubleshooting Electric Blanket

                                  It will be fine to try, that way you will know if it is going to fix it or not.

                                  Comment


                                    #37
                                    Re: Troubleshooting Electric Blanket

                                    OK, I'll give the 103 a try later on and post feedback.

                                    Originally posted by R_J View Post
                                    It will be fine to try, that way you will know if it is going to fix it or not.

                                    Comment


                                      #38
                                      Re: Troubleshooting Electric Blanket

                                      I've installed the 103 resistor and the LED is now on. Haven't checked it properly with the blanket element yet.

                                      I still have the 1002 on order, so I'll replace with that as soon as I have it

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                                        #39
                                        Re: Troubleshooting Electric Blanket

                                        103 and 1002 are the same part,
                                        the current/wattage is not printed on them but is implied by the physical size!

                                        Comment


                                          #40
                                          Re: Troubleshooting Electric Blanket

                                          Good to here it's up and working, I wish I would have noticed the missing resistor earlier, It was'nt untill I was tracing the low voltage circuit that I noticed it.

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