Sharp lc-c32d42u no standby

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  • crosstalk
    Senior Member
    • Feb 2014
    • 68
    • Usa
    #1

    Sharp lc-c32d42u no standby

    Hi. I have no standby on this power supply in a sharp lc-32d42u. I found D7907 (1N5383B) shorted, so I replaced that and IC7905 (TNY268PN). I have 160vdc on the drain pin of the IC, 0vdc on the source, and 2.2vdc on the EN pin of the IC. I thought maybe the first replacement IC was a bad part, but trying a second one didn't help--still 0v on the 5vdc standby output.

    What else should I be checking?
    Attached Files
    Last edited by crosstalk; 03-07-2017, 01:43 PM.
    Tags: None
    • dick_barton
      Badcaps Legend
      • Aug 2015
      • 6642
      • Wales
      #2
      Re: Sharp lc-c32d42u no standby

      More details in the following thread

      https://www.badcaps.net/forum/showth...ight=lc-32d42u
      Willing to help but I'm no expert.

        Comment

        • crosstalk
          Senior Member
          • Feb 2014
          • 68
          • Usa
          #3
          Re: Sharp lc-c32d42u no standby

          Thanks. I saw that thread too. I checked D7908 and the other diodes near the photocouplers and they were ok. There could be other problems in that area--I'm not too sure how the photocoupler setup on the secondary side is supposed to work to feedback to the smps IC.

            Comment

            • dick_barton
              Badcaps Legend
              • Aug 2015
              • 6642
              • Wales
              #4
              Re: Sharp lc-c32d42u no standby

              So D7908 & D7907 both checked out OK.
              What dc voltage do you have between pins 1 & 3

              With the power to the set off what is the resistance of TNY268 between pins 5 and pin 8?
              Attached Files
              Last edited by dick_barton; 03-07-2017, 04:47 PM.
              Willing to help but I'm no expert.

                Comment

                • crosstalk
                  Senior Member
                  • Feb 2014
                  • 68
                  • Usa
                  #5
                  Re: Sharp lc-c32d42u no standby

                  Yes those diodes checked out ok. I have 3.53vdc between pins 1 and 3 and 4.24kohms between 5 and 8.

                    Comment

                    • dick_barton
                      Badcaps Legend
                      • Aug 2015
                      • 6642
                      • Wales
                      #6
                      Re: Sharp lc-c32d42u no standby

                      There is a repair kit
                      http://www.ebay.co.uk/itm/SHARP-Powe...-/141906829894
                      Willing to help but I'm no expert.

                        Comment

                        • crosstalk
                          Senior Member
                          • Feb 2014
                          • 68
                          • Usa
                          #7
                          Re: Sharp lc-c32d42u no standby

                          Thanks for your help. I got it working. Looked more carefully and found R7902D open. Replaced that and 5v standby is back and the tv is working.

                            Comment

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