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Magnavox 37mf321d/37

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    #1

    Magnavox 37mf321d/37

    Hello everyone, my friend owns a Magnavox 37mf321d/37 that has been playing up for a while now. I have been reading every thread on this forum talking about issues of that tv but I couldn't find anyone with the same symptoms as my friends. When he powers on the tv it gets stuck on the start screen for about 5-10 minutes and then it just works fine... Any ideas on what could be the problem?? Is this related to the common bad capacitors and diodes on the power supply board or could it be the main board or what could it be? any help is much appreciated! thanks in advance! cheers!!
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    #2
    Re: Magnavox 37mf321d/37

    what happens if the tv ran for some time, then turn it off and than back on again?

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      #3
      Re: Magnavox 37mf321d/37

      Sorry for the late reply but I had issues with my broadband connection which is finally fixed now! It seems like all the electronics are failing on me lately ahah! The tv gets stuck on the settings screen from anywhere between 5 to 9 minutes when first started. I can hear the sound of the tv channel on the background but if i scroll down and click on exit, it goes back to the settings screen. After 4 or 5 minutes i can actually see the tv channel for a few seconds after pressing exit, but eventually the settings screen will come up again. At about 9 minutes if I scroll down and click on exit the tv works as normal. If I turn the tv off and then turn it on straight away it still works as normal. If I leave it off for about 5 minutes and then turn it on, I get the settings screen for about a couple of minutes. If I leave the tv off for about 10 minutes or over, the setup screen will be up for about 9 minutes again. All of this was happening until yesterday but now all of a sudden the tv won't even turn on. I just get a black screen with backlight, the power button is steady green, but no image or sound or settings menu. I have opened it and had a look at it and didn't see any damaged capacitors or burn marks on either the power board or the mother board. The power board seems to have had some work done to it and at least one capacitor must have been replaced. The capacitor at position 2074 has been replaced with a 50v 2200uF capacitor, the ones at position 2080 and 2082 are 35v 1000uF and the one at position 2081 is 35v 1200uF. I was wondering if this capacitors are the correct ones? I don't think the zener diodes have been replaced and they do not look burnt or damaged. The mother board looks good. I was thinking of getting a new motherboard for it and I was wondering if that is a good idea or not? Or could it be something else? Thanks in advance for any advice!!

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        #4
        Re: Magnavox 37mf321d/37

        Well... you have a main board problem. So yes, it would have to be replaced.

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          #5
          Re: Magnavox 37mf321d/37

          Could that even be a power board issue? Or is it a main board issue most likely? also which one is the part number? on the front of the main board it says 3138 013 6294.3 on the back of the board it says 8238 273 8271.3gps and on a white sticker with a barcode it says 3138 158 68211? I have found on the internet a used main board ''Philips 313815866271 (31381036284.3) Scaler Board For 37MF321D/37'' would this be the right board? Thanks so much again for your help

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            #6
            Re: Magnavox 37mf321d/37

            Not having any measurements, but from what you are saying in first post that the TV actually came on. So the PSU must have been working at that point and you are having a main board fault.
            Right now you report no picture no sound, but backlights on: So your mainboard is sending PSon and BLon, but not working otherwise. Means to me the PSU should be good, but I can't proof it without any measurements. Unfortunately there are no pinouts available (on SJ photos).
            You also could not have any picture at all because the Tcon board is bad. You can proof this buy using an oscilloscope and look at the LVDS off the main board.
            So right now as things stand, I'd be going for the main board first, unless you come up with some measurements.

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              #7
              Re: Magnavox 37mf321d/37

              Thanks for your advice! I have just purchased a main board off the internet and I should get it by next week... I will let you know if that fixed the problem! In case somebody else has the same problem, after doing some research I found out that this main boards parts numbers are interchangeable and would all work for the magnavox 37mf321d/37:
              313815868211
              313815866271
              313815864951
              313815866861
              313815866881
              313815868521
              313815868281
              313815868221
              Thanks again for your help!

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                #8
                Re: Magnavox 37mf321d/37

                Hi, thanks to your advice, after replacing the main board twice (the first time I was sent the wrong board) I finally got the tv to work!! The main board only costed me only 32.75 USD including shipping so I'm very happy about that!! The only small issue is that I get a high pitched whistle for about 10 minutes when I turn the tv on... after that the whistle slowly goes away. It does not come from the speakers. I took the tv apart and tried listening many times but I cannot find out where the whistle is coming from. I tried placing a thick towel over the power supply first, then the main board and then the t-con board but I cannot figure it out... somehow it seems to me that the whistle might be coming from the t-con board... is it possible that the t-con board causes that issue? Oh and also the whistle gets louder when the picture is white but it becomes almost quiet when the picture is black. Does anybody have any experience in solving this issue? Thanks so much again for your help!!

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                  #9
                  Re: Magnavox 37mf321d/37

                  I think your power supply needs new caps, and maybe the diode kit, they make the transformer whine. Search that. You will find lots of help.

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                    #10
                    Re: Magnavox 37mf321d/37

                    Good to hear you got your TV fixed. My bet on the whine is the PSU.
                    If you think you need a cap replacement on the PSU, then take a hair dryer and heat up the power supply capacitors until everything is nice and warm, but not hot that you can't touch it. Turn on the TV and see what happens. You can use that warm up technique on any board. The reason for this: When a electrolytic capacitor get's warm, the ESR value drops.

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                      #11
                      Re: Magnavox 37mf321d/37

                      That would make perfect sense! I think I will just leave the tv as it is for the moment and see if I can deal with a few minutes of whistling... I do not want to spend anymore money to fix this tv... it is good enough for now! Thanks for your help!! Great forum!!

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                        #12
                        Re: Magnavox 37mf321d/37

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