LG 50PC55 Plasma Vertical Bars!

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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK
    #21
    Re: LG 50PC55 Plasma Vertical Bars!

    It could easily cause the symptoms. "No signal" is not the fault. It is just because no input is connected.
    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

      • studfish
        Member
        • Dec 2013
        • 23
        • uk
        #22
        Re: LG 50PC55 Plasma Vertical Bars!

        Hi Tom thanks but even when i have devices connected and change the input using the controls on the tv i still get no signal.......... main board?

        Also if i press the menu button the tv turns off .

        The Red standby light does not change either it just goes from red to off
        Last edited by studfish; 12-08-2013, 06:32 AM.

          Comment

          • studfish
            Member
            • Dec 2013
            • 23
            • uk
            #23
            Re: LG 50PC55 Plasma Vertical Bars!

            just as an update......

            I changed the mainboard and now the standby light turns from red to green so there must have been some kind of problem with the original.... all other problems remain however

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK
                #24
                Re: LG 50PC55 Plasma Vertical Bars!

                Could just be different config/software on main board. Doubt main board was bad. 99% Y-buffer, 1% Y-sustain (if -Vy or Vsc askew.)
                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

                  • Glitcher
                    Badcaps Veteran
                    • Mar 2013
                    • 673
                    • USa
                    #25
                    Re: LG 50PC55 Plasma Vertical Bars!

                    Common problem would be a blown IC on one of the buffer boards. Just a guess but it is a FQB46N15? If it is then replacing it should fix the problem.

                      Comment

                      • studfish
                        Member
                        • Dec 2013
                        • 23
                        • uk
                        #26
                        Re: LG 50PC55 Plasma Vertical Bars!

                        gone over the power supply with a fine tooth comb and found a bulged 250v 820uf cap (dont ask how i missed it) guess that need replacing before i go any further

                          Comment

                          • Alastair E
                            Chief Womble
                            • Mar 2013
                            • 1963
                            • U.K.
                            #27
                            Re: LG 50PC55 Plasma Vertical Bars!

                            IF you have Vertical bars on the pic, then there's a high chance the Address Chip associated with that area of the screen is stuffed.

                            These chips are found along the Bottom edge of the screen and are often part to the flexible connection to the screen--and are part of the screen and not replaceable.
                            --If so, then you'll need a new plasma panel......

                            The dead/int dead could well be a protection system coming in due to the stuffed chip....
                            TELEFIX

                            How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
                            http://www.irf.com/technical-info/appnotes/an-1088.pdf
                            PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

                              Comment

                              • studfish
                                Member
                                • Dec 2013
                                • 23
                                • uk
                                #28
                                Re: LG 50PC55 Plasma Vertical Bars!

                                Im still after getting this tv repaired so i have uploaded a short video of the problem I would appreciate it if someone could tae the time to have a look
                                Thanks
                                Kev
                                Attached Files

                                  Comment

                                  • studfish
                                    Member
                                    • Dec 2013
                                    • 23
                                    • uk
                                    #29
                                    Re: LG 50PC55 Plasma Vertical Bars!

                                    Ive just checked the va and vs voltages and wondered if there within tollerance?

                                    The va is suppose to be 60 but is reading 55.2
                                    The vs is suppose to be 190 and is reading 188.6

                                      Comment

                                      • Glitcher
                                        Badcaps Veteran
                                        • Mar 2013
                                        • 673
                                        • USa
                                        #30
                                        Re: LG 50PC55 Plasma Vertical Bars!

                                        One of your Y-Buffers are bad... You need to replace the blown FET IC on it.

                                        If you find that after replacing the FET, the problem is still there, you need to check it again as it may have blown again.

                                        Its a common problem and usually the FET will blow again if your Y-Sustain is starting to go bad.

                                          Comment

                                          • studfish
                                            Member
                                            • Dec 2013
                                            • 23
                                            • uk
                                            #31
                                            Re: LG 50PC55 Plasma Vertical Bars!

                                            Thanks the top y-buffer is bad so ive done the va vs test with them dissconected would this make a difference?

                                              Comment

                                              • Glitcher
                                                Badcaps Veteran
                                                • Mar 2013
                                                • 673
                                                • USa
                                                #32
                                                Re: LG 50PC55 Plasma Vertical Bars!

                                                I don't think the VA or VS voltages would change whether or not the buffers are disconnected.

                                                  Comment

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