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MAGNAVOX no picture powers LED 47MF437B/37

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    #1

    MAGNAVOX no picture powers LED 47MF437B/37

    Hello, I an new to this forum and want to thank you all for the incredible jon you do. I am a novice/ intermed. with electronics.. my experience is mor with computers. Okay my problem, much like many others. I replaced 3 bad caps. However, when I out the power chord in the red LED goes on then I get what I would best describe as a CHIRP. Any thoughts. beseides caps model #47MF437B/37
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    #2
    Re: MAGNAVOX no picture powers LED 47MF437B/37

    I think I may have worked on one of these once. If you've already replaced all four caps (whether visually bad or not) then list the voltages that you get on the output of this supply.
    The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

    Comment

      #3
      Re: MAGNAVOX no picture powers LED 47MF437B/37

      If you type in the model number "47MF437B" on the site below, you can get a service manual for this set. This should help you out a great deal with this problem. Just remember, the caps may have took something out with it.

      http://elektrotanya.com
      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

      Comment

        #4
        Re: MAGNAVOX no picture powers LED 47MF437B/37

        I looked at that sight is very difficult to navigate. I will work on downloading that manual. If anybody has any other suggestions, please dire away.
        Thank for your help.

        Comment

          #5
          Re: MAGNAVOX no picture powers LED 47MF437B/37

          Power board schematic taken from the service manual PDF. You're really gonna want to download the manual if you need it clearer. This site has a limit for posting pdf files for attachments.
          Attached Files
          Last edited by Dgtech; 11-13-2011, 05:28 AM.
          The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

          Comment

            #6
            Re: MAGNAVOX no picture powers LED 47MF437B/37

            Thanks for posting that for me. However, being a novice to all this. The picture I see is one VERY VERY difficult to decipher. Any suggestions on where to start. I get the red power LED to light up,
            - then press the power button and I get the chirp, chirp chirp. Strange though even though I replaced my bad caps. That same sound happened before I replaced them.

            So , the three ne caps changed nothing.

            Thanks

            Van

            Comment

              #7
              Re: MAGNAVOX no picture powers LED 47MF437B/37

              Originally posted by van18 View Post
              Thanks for posting that for me. However, being a novice to all this. The picture I see is one VERY VERY difficult to decipher. Any suggestions on where to start. I get the red power LED to light up,
              - then press the power button and I get the chirp, chirp chirp. Strange though even though I replaced my bad caps. That same sound happened before I replaced them.

              So , the three ne caps changed nothing.

              Thanks

              Van
              A 'chirping' sound usually indicates a bad startup cap, a shorted diode on the secondary of the transformer, or an excessive load. Because of the usual design of these power supplies, it's probably not a startup cap.

              PlainBill
              For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

              Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

              Comment

                #8
                Re: MAGNAVOX no picture powers LED 47MF437B/37

                Thanks PlainBill,

                I am presently trying to get a picture of the PSU up for all to look at. Then Maybe you or anyone else kind enough, might have some specific advice.

                Comment

                  #9
                  Re: MAGNAVOX no picture powers LED 47MF437B/37

                  Pics of PSU with three new caps, Still chirping, no picture.
                  Attached Files

                  Comment

                    #10
                    Re: MAGNAVOX no picture powers LED 47MF437B/37

                    There is a fourth electrolytic cap, the green one. I would change this as well to be on the safe side.
                    The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                    Comment

                      #11
                      Re: MAGNAVOX no picture powers LED 47MF437B/37

                      Dgtech,

                      Are you refffering to the green capacitor? I am not sure if there is a difference between the two?

                      Thanks again for the help!!

                      Comment

                        #12
                        Re: MAGNAVOX no picture powers LED 47MF437B/37

                        <rant>

                        Damn, and I used to think of Philips as good.

                        I opened up a 37PFL7662D/05, not that old. Full of Rubycon and Nichicon. A 32PFLxxxx (forget the full number) had Rubycon, Nichicon and Chemicon... all very good caps.

                        That power supply looks like they put caps on it that they found in the bin or on the factory floor. Why is one of the three 2200u/35V caps larger?

                        Ugh, I suppose even good engineering goes to the wayside when bean counters get involved.

                        </rant>

                        I have several working supplies that chirp when power is lost, I think it's possibly to do with the frequency of the switcher changing to keep the voltage stable as the bulk cap discharges. But the chirping when trying to turn on is definitely a problem.

                        There is a startup cap on this model C957 bottom center.
                        Last edited by tom66; 11-14-2011, 09:29 AM.
                        Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                        For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                        Comment

                          #13
                          Re: MAGNAVOX no picture powers LED 47MF437B/37

                          I will try to replace all caps. Just to see what up. Although if I can get a picture of it the LARGE YELLOW TAPED piece in the middle looks like it horrible corrodided at the bottom. Guys anything else? Thanks for the help thus far

                          Comment

                            #14
                            Re: MAGNAVOX no picture powers LED 47MF437B/37

                            Can anyone help me make heads or tales out of this?

                            http://www.scribd.com/doc/68245090/5...-0u-la-sm-ET-1

                            Thanks

                            Comment

                              #15
                              Re: MAGNAVOX no picture powers LED 47MF437B/37

                              Originally posted by van18 View Post
                              Dgtech,

                              Are you refffering to the green capacitor? I am not sure if there is a difference between the two?

                              Thanks again for the help!!
                              You said that you replaced three caps but there are four on the board. Did you replace all four or just three? That green cap looks like a capxon capacitor. I would not skip changing this one.
                              The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                              Comment

                                #16
                                Re: MAGNAVOX no picture powers LED 47MF437B/37

                                Dgtech,

                                Yes, I went ahead and and changed that out on your advise. Still loud chrip when I power up. FRUSTRATED!!!!

                                Thanks

                                van

                                Comment

                                  #17
                                  Re: MAGNAVOX no picture powers LED 47MF437B/37

                                  I dont know if you've seen this thread but check it out if you didnt. Similar power board from Magnafraud.

                                  https://www.badcaps.net/forum/showth...light=MAGNAVOX
                                  The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

                                  Comment

                                    #18
                                    Re: MAGNAVOX no picture powers LED 47MF437B/37

                                    Some pictures of the actual PSU we are working on from MAGNAVOX no less
                                    Attached Files

                                    Comment

                                      #19
                                      Re: MAGNAVOX no picture powers LED 47MF437B/37

                                      hey, I have managed to get my hands on a repair manual. This is great news!! It would be even better if i could figure out what is what in it. Sorry guys I am really a novice. I can tell you the voltage something is running but I dont know thats a good or bad thing.

                                      Any help would be greatly appreciated!!

                                      SV

                                      Comment

                                        #20
                                        Re: MAGNAVOX no picture powers LED 47MF437B/37

                                        Hello again from the STRUGGLING NEWB!!!! I have noticed that the T907 Trans (PIC ATTACHED....ALSO PLEASE CONFIRM OR SUGGEST A MODEL NUMBER TO THIS PIECE SO I CAN BUY IF AVAILABLE.

                                        Thanks you for you help

                                        PICTURE 1 is my entire PSU with TRANS BLOCKED IN YELLOW

                                        PICTURE 2 CLOSE UP OF ITEM IN QUESTION

                                        PS PLEASE HELP
                                        Attached Files

                                        Comment

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