LG 50PQ6000 unstable 5v standby

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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #121
    Re: LG 50PQ6000 unstable 5v standby

    I think modding one in would lead to poorer performance.

    A diode's current rating is determined by both the size of the die (high current density destroys the device) but MAINLY decided by the amount of heat it can remove (0.6V at 3A ~ 1.8W, must be able to get rid of this without overheating.)
    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

    • Baileybum1234
      Badcaps Veteran
      • Sep 2012
      • 245
      • UK

      #122
      Re: LG 50PQ6000 unstable 5v standby

      Use the 5v and add a mini pc fan directed at the diode? Maybe.
      Repaired: LG50PQ6000

      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #123
        Re: LG 50PQ6000 unstable 5v standby

        Might help, but a mini fan will screeeeeeam in standby mode.
        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

        • Baileybum1234
          Badcaps Veteran
          • Sep 2012
          • 245
          • UK

          #124
          Re: LG 50PQ6000 unstable 5v standby

          Ok back at home now, I was using the smart phone while working away its some what challenging.

          So is there a way to test the control board to see if some component is faulty and pulling too mutch current through that diode and making it go O/C? OR am I totally wrong with that theory do you think?
          Repaired: LG50PQ6000

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #125
            Re: LG 50PQ6000 unstable 5v standby

            No, I doubt that's the issue. The diode is simply running too hot.
            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

            • Baileybum1234
              Badcaps Veteran
              • Sep 2012
              • 245
              • UK

              #126
              Re: LG 50PQ6000 unstable 5v standby

              ok then maybe the replacement I found had a slightly different spec to the original. I will have a proper look later online.
              Repaired: LG50PQ6000

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #127
                Re: LG 50PQ6000 unstable 5v standby

                Yeah, it was 150V rated instead of 200V. The new one is 200V.
                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

                • Baileybum1234
                  Badcaps Veteran
                  • Sep 2012
                  • 245
                  • UK

                  #128
                  Re: LG 50PQ6000 unstable 5v standby



                  So I wounder what would happen if I put one of these in instead?

                  Manufacturer's Part Number: SF47G R0

                  4A 500V 35ns Super Fast Rectifier Glass Passivated



                  Repaired: LG50PQ6000

                  Comment

                  • tom66
                    EVs Rule
                    • Apr 2011
                    • 32560
                    • UK

                    #129
                    Re: LG 50PQ6000 unstable 5v standby

                    It's not a schottky diode (low loss type), but it may work.
                    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

                    • ben7
                      Capaholic
                      • Jan 2011
                      • 4059
                      • USA

                      #130
                      Re: LG 50PQ6000 unstable 5v standby

                      If the original shottky diode got hot and fried, then that diode will certainly fry faster!

                      tom66, why you think it would lead to poorer performance? A heatsink could be added to the TO-220 device also, to keep it cooler. I don't understand how that would lead to poorer performance :S
                      Muh-soggy-knee

                      Comment

                      • tom66
                        EVs Rule
                        • Apr 2011
                        • 32560
                        • UK

                        #131
                        Re: LG 50PQ6000 unstable 5v standby

                        Because a TO220 device with a crappy heatsink is going to be just as limited as that package. Maybe it would run a little cooler, but the correct solution is to find the right diode.
                        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

                        • Baileybum1234
                          Badcaps Veteran
                          • Sep 2012
                          • 245
                          • UK

                          #132
                          Re: LG 50PQ6000 unstable 5v standby

                          I thought I found the right diode when I fitted the VSB3200 and it fried :0/
                          Repaired: LG50PQ6000

                          Comment

                          • ben7
                            Capaholic
                            • Jan 2011
                            • 4059
                            • USA

                            #133
                            Re: LG 50PQ6000 unstable 5v standby

                            Originally posted by tom66
                            Because a TO220 device with a crappy heatsink is going to be just as limited as that package. Maybe it would run a little cooler, but the correct solution is to find the right diode.
                            Ah, so you mean like a fast enough recovery time, reverse current, and capacitance?

                            The original diode, a VSB3200 claims that it is a high-efficiency diode (VF=0.63V) - the SMPS is designed terribly because of that 'high-efficiency' diode overheating!

                            Really should get a new test diode, and then scope the diode, to see if it really needs to be a 200v diode.
                            Muh-soggy-knee

                            Comment

                            • Baileybum1234
                              Badcaps Veteran
                              • Sep 2012
                              • 245
                              • UK

                              #134
                              Re: LG 50PQ6000 unstable 5v standby

                              Originally posted by ben7

                              Really should get a new test diode, and then scope the diode, to see if it really needs to be a 200v diode.
                              Shame I have one more VSB3200 test diode but no scope. Guess it cant be done on a DVM?
                              Repaired: LG50PQ6000

                              Comment

                              • tom66
                                EVs Rule
                                • Apr 2011
                                • 32560
                                • UK

                                #135
                                Re: LG 50PQ6000 unstable 5v standby

                                It's definitely a VSB3200? Not incorrect part? CHS have done that to me before!!!
                                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

                                • Baileybum1234
                                  Badcaps Veteran
                                  • Sep 2012
                                  • 245
                                  • UK

                                  #136
                                  Re: LG 50PQ6000 unstable 5v standby

                                  Well if I look at the original its markings are:

                                  VSB3200
                                  M944A

                                  and the replacement was:

                                  SB3200
                                  1142

                                  (eventhough the CHS label says: VSB3200 DIODE GENERAL) You could be right here Tom.
                                  Repaired: LG50PQ6000

                                  Comment

                                  • tom66
                                    EVs Rule
                                    • Apr 2011
                                    • 32560
                                    • UK

                                    #137
                                    Re: LG 50PQ6000 unstable 5v standby

                                    It looks to be similar.


                                    Odd that it failed quicker than the 150V diode!
                                    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

                                    • Baileybum1234
                                      Badcaps Veteran
                                      • Sep 2012
                                      • 245
                                      • UK

                                      #138
                                      Re: LG 50PQ6000 unstable 5v standby

                                      Originally posted by tom66
                                      It looks to be similar.


                                      Odd that it failed quicker than the 150V diode!
                                      Im still not sure where the 150v diode came in (confused.com)? I never used a 150v diode just went straight to the (what I thought was a VSB3200) SB3200 as a replacement thinking it would be a better option?
                                      Last edited by Baileybum1234; 12-23-2012, 09:15 AM.
                                      Repaired: LG50PQ6000

                                      Comment

                                      • Baileybum1234
                                        Badcaps Veteran
                                        • Sep 2012
                                        • 245
                                        • UK

                                        #139
                                        Re: LG 50PQ6000 unstable 5v standby

                                        I wounder if I should have a moan at CHS.
                                        Repaired: LG50PQ6000

                                        Comment

                                        • tom66
                                          EVs Rule
                                          • Apr 2011
                                          • 32560
                                          • UK

                                          #140
                                          Re: LG 50PQ6000 unstable 5v standby

                                          I thought I linked you to the 150V part on Farnell?

                                          I would think that if the original diode lasted -X- years then their replacement can also be expected to last -X- years.

                                          So I would think the diode isn't a directly substitutable part, you need to find a VSB3200 not an SB3200.
                                          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

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