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Samsung 50" Plasma HPT5044 No Picture

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    Re: Samsung 50" Plasma HPT5044 No Picture

    Pic seems pretty bright. What do I need an xmain again for ?
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      Re: Samsung 50" Plasma HPT5044 No Picture

      Let me post up a pic of the xsus...

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        Re: Samsung 50" Plasma HPT5044 No Picture

        try heating the X-main and PSU and see if the problem occurs quicker.
        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.

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          Re: Samsung 50" Plasma HPT5044 No Picture

          The ysus is operating normally as per the previous pic so I would think my problems lie with the xmain. What components did you replace on that LG with the bad Vzbias ?

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            Re: Samsung 50" Plasma HPT5044 No Picture

            Just the regulator FET, and the original two Vzbias-drive FETs that blew (causing the fault in the first place)
            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.

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              Re: Samsung 50" Plasma HPT5044 No Picture

              I think he didn't test the fets under the heat sink correct. Test them on just ohms no diode mode and it may be the end of all this.

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                Re: Samsung 50" Plasma HPT5044 No Picture

                You may find a short on one or all...

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                  Re: Samsung 50" Plasma HPT5044 No Picture

                  Still chasing my tail with this one but here's an update...

                  There was no problem with VS or the power supply etc. Had this notion that I should recheck VS AFTER the screen lit up and sure enough was set way too high. Setting it as per panel sticker solved that. -> Idiot Award <- lol

                  Now, I have a good ysus, xsus and an upper and lower buffer each with a scan ic missing. I installed the last ic on the upper buffer and when I ran the set the picture area drawn by that ic had extreme noise so I pushed gently on it with the rubber end of a screwdriver to see if it was a contact issue and *Pop* went that ic.

                  I removed it and checked that both buffers were good and now when I run the set I get NO picture on the lower half of the screen although it is lit (upper half is the "no signal" w/blue background).

                  So my question is I know the signal from the control board runs through the ysus so did I damage something on it and if so where should I look ? Or did I damage the control board itself ?
                  Last edited by mmartell; 09-15-2014, 02:41 AM.

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                    Re: Samsung 50" Plasma HPT5044 No Picture

                    Ok not the ysus, had another here and symptoms are the same.

                    Pic might not show the bottom half of the screen well but it's glowing.

                    I know the signal is daisy-chained from upper to lower. Is there an easy way to tell which buffer is at fault since they both test free of shorts ?
                    Attached Files
                    Last edited by mmartell; 09-15-2014, 08:03 AM.

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                      Re: Samsung 50" Plasma HPT5044 No Picture

                      Will probably be 3rd or 4th on that board, hard to be certain which.
                      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.

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                        Re: Samsung 50" Plasma HPT5044 No Picture

                        Ya the fourth buffer ic is not installed thats why the second quadrant looks a little dimmer. The problem is there is no picture in the bottom half of the screen (lower buffer is installed) even though the screen is lit up. Is the lower buffer bad somehow (there are no shorts) or is the upper buffer not passing down the signal to it and how would I find out ?

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                          Re: Samsung 50" Plasma HPT5044 No Picture

                          Without that 4th chip, data won't get to the rest of the buffer ICs.
                          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.

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                            Re: Samsung 50" Plasma HPT5044 No Picture

                            Hmm.. I've done too many permutations I think I may be confusing myself...

                            So the upper buffer can be missing the FIRST scan ic and still show a pic on the top half but the 4th ic must be installed to pass scan info to lower buffer ? Ok thanks for that will get the other two ic's installed and see what I get.

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