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Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

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    Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

    The video on my 58" Samsung plasma stopped working a couple weeks ago. When powering on, it would click a few times like normal, but the screen would never power on. The screen does not glow, but there is audio.

    I opened it up and noticed that an arc would occur a few seconds after powering up - on what I think is a surface mount capacitor (attached image) on the lower Y buffer. I disconnected the lower buffer and powered on the TV and the upper half of the screen came on. I tried the same test with the lower buffer and the bottom half of the screen came on, but it wasn't clean. After a couple power on/off cycles, the capacitor started smoking and the lower half won't come on anymore.

    After reading that buffer/y main boards should be replaced together, I ordered both buffers and the y main board and installed all three. Upon powering up with all boards connected, I still have audio but no video. I can get the upper half of the screen to come on though. Here is my current situation:
    • Both buffers connected - no video
    • Upper buffer only connected - video on upper half
    • Lower buffer only connected - no video


    There is no visual damage on this new lower buffer, but I performed the buffer short test with a DMM and found several traces on the buffer board that reported shorts.

    Is it possible that the screen damaged the new buffer? I did not check the buffer for shorts prior to installation, so I don't know if it came defective. I can not see any cracks on the screen or edge of the screen, and the TV was not bumped/impacted prior to the video failing.

    Are there any other tests that could tell me if putting another lower buffer on will damage that one?

    I've attached pics of the original lower buffer before/after burning up. You can see a small crack in the capacitor C5503 that was arcing on power up. The picture of the lower screen was taken prior to the capacitor burning up. I can only get the upper half to come on now.
    Attached Files

    #2
    Re: Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

    Maybe clean up the board and remove the shorted ic and try running it with one ribbon plugged in at a time ?

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      #3
      Re: Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

      It is fairly common on plasmas that you can only get 1/2 a pic with one of the buffers installed - in fact I only know of a few Panasonic models which will give you 1/2 pic in both cases.

      Did the failed resistor occur in the same area as the outputs tested bad? For example did you only get shorts on the top most ribbon. That could indicate a panel short although that would be bad luck because AFAIK, there are no reports of panels killing buffers on these sets...
      Last edited by tom66; 07-23-2014, 12:40 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


        #4
        Re: Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

        There were shorts on the top and middle outposts. The burned out resistor is above the top outpost, right next to it. I have another lower buffer being shipped today. I'll test it before installing it.

        So that surface mount component is a resistor and not a capacitor? I was thinking that the R,D,C prefixes were for resistor, diode, capacitor.

        If I didn't connect all three ribbon cables from the panel to the buffer board, should I get some output on the lower half if the ICs for the connected outpost(s) are good?
        Last edited by brad_c; 07-23-2014, 09:56 AM.

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          #5
          Re: Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

          Yes you can run the TV with just some ribbons installed, just make sure not to partially install them (they must be fully installed or not at all)
          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


            #6
            Re: Samsung PN58B860 lower buffer failed and replacement seems to have failed as well

            The new lower buffer came in yesterday. Tested for shorts and it passed. Installed it and the TV now works perfectly.

            However, when I powered it on, the picture had a blue tint to it using all inputs, but all overlays looked fine. So I found a "blue only" menu option used for checking hue and saturation that somehow got enabled.

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