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LG bh9530tw home theater no power

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    #21
    Re: LG home theater no power

    Originally posted by R_J View Post
    Maybe if you posted the service manual with smps schematic (post#8) others could help.
    Yes this would be nice

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      #22
      Re: LG home theater no power

      push

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        #23
        Re: LG home theater no power

        push

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          #24
          Re: LG home theater no power

          Did you try PM DJKRISH to see if he can upload the schematic?
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

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            #25
            Re: LG home theater no power

            No

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              #26
              Re: LG home theater no power

              So what exactly is wrong with YOUR power supply, maybe we can figure it out. Post a picture and list what parts you have found that are defective so far.

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                #27
                Re: LG home theater no power

                Originally posted by R_J View Post
                So what exactly is wrong with YOUR power supply, maybe we can figure it out. Post a picture and list what parts you have found that are defective so far.
                Hey thank you for your patience

                I will make pictures tonight and upload these here

                My Player wont turn on. Nothing happen when pushing the power button on the remote control. No lights nothing

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                  #28
                  Re: LG home theater no power

                  This are the pictures of the board i have on phone. Better pictures i can make when i am at home.
                  Attached Files

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                    #29
                    Re: LG home theater no power

                    "Ye olde" crapped-out start-up cap problem, perhaps?
                    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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                      #30
                      Re: LG home theater no power

                      The caps looking all good...

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                        #31
                        Re: LG home theater no power

                        That is positively irrelevant, especially in those smaller can sizes. Just because they haven't exploded, doesn't mean they haven't dried out and/or dramatically lost capacitance.

                        https://en.wikipedia.org/wiki/Bootst...power_supplies
                        Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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                          #32
                          Re: LG home theater no power

                          Originally posted by Khron View Post
                          That is positively irrelevant, especially in those smaller can sizes. Just because they haven't exploded, doesn't mean they haven't dried out and/or dramatically lost capacitance.

                          https://en.wikipedia.org/wiki/Bootst...power_supplies
                          Ok should i replace all caps ?

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                            #33
                            Re: LG home theater no power

                            So here are another two pictures.


                            I measured the voltages on the PCB board on the contacst you see on picture 1. But my measure doesnt match with the voltages written on the PCB.
                            Attached Files

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                              #34
                              Re: LG home theater no power

                              For starters, i'd replace C909, C919(?) and C936, preferably with name-brand, low-ESR ones.

                              And how far off are the voltages you're measuring?
                              Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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                                #35
                                Re: LG home theater no power

                                The voltages that i measure are not constant. They jumping from for ex. 4-16v etc...

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                                  #36
                                  Re: LG home theater no power

                                  I will replace C909, C919 and C936 with new low-ESR ones and measure the voltages again and look if i can turn on the player.

                                  Actually i can not turn on the Player its dead. I will write here again after i change the Caps.

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                                    #37
                                    Re: LG home theater no power

                                    ... Which may well be an indication of the "hiccup"-mode the PWM chip is in, not being able to start and keep working.

                                    So either (one of) those three capacitors i indicated has failed, or (maybe a bit less likely) there's some shorted diode on the associated secondary.
                                    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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                                      #38
                                      Re: LG home theater no power

                                      I will change the three capacitors and see whats going on after this and then i wil lwrite here again

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                                        #39
                                        Re: LG home theater no power

                                        You know the capacitors farad and volts that i need? Then i can order they directly now. Otherwise i must wait until tonight when i am back home after work.

                                        Do you have the schematic maybe ?

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                                          #40
                                          Re: LG home theater no power

                                          I can't really see the values from the photos you've posted.

                                          No, i don't have the schematic, but for sort-of-"textbook" circuits like these, manufacturers rarely make things much more complicated than the datasheet examples of the chips they use. In this case, that 7-pin chip driving that transformer seems to be a Sanken STR-A6053M.

                                          https://cdn.badcaps-static.com/pdfs/...ae6914545d.pdf

                                          Example schematics are on page 12.

                                          C909 is most likely the filter capacitor for the chip's Vcc line (C2 in the example-schematics), so that would be the prime suspect, given the symptoms. Something like a 47u/50v should be fine, in that position. C936 may well be a similar value, and the fatter one between them, possibly 100uF/50v (the voltage rating is visible).
                                          Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

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