Proscan 42LA45H PSU Problem

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  • Nr1Ctr
    Member
    • Oct 2015
    • 22
    • USA

    #1

    Proscan 42LA45H PSU Problem

    Hello all!

    I've got a Proscan 42LA45H LCD flatscreen that has PSU issues that I'm trying to fix. I looked at the other posts related to this TV and particular board but the problem I'm having seem different. The unit has standby power but will not turn on. This first thing I checked, thanks to you all and others on google, was the caps. I found one that was obviously bad and changed it out. The others looks fine, but I have no way to test them as all I have is a cheap DVM.

    There is also a humming noise coming from the PSU board after I plug it in, and I'm not really sure if it was there before I changed the cap. I checked all the voltages coming off the board and they are as follows:

    gnd - 0
    gnd - 0
    sw - 4.24v
    sw5 - 4.96v
    sw5 - 4.96v
    12/5 - 0.12v
    12/5 - 0.12v
    gnd - 0
    br? - 0
    on - 0
    gnd - 0
    gnd - 0
    m5v - 0.01v
    m5v - 0.01v

    I have attached pictures of the board with the new cap and a pic of what I took to be the bad (old) cap. If anything else is needed please let me know. I'm really just looking for ideas of where to go from here. I got this set for free, courtesy of someone who dropped it off at the dumpster by my place. Figured if I could change a couple caps, or something cheap anyways, it would make a nice Christmas present for the kids. If not, ill just haul it back out there. Thanks all, and I look forward to talking to you.

    edit: Also, I assume that light at VD824 (bottom) is supposed to light up, but it doesn't.
    Attached Files
    Last edited by Nr1Ctr; 10-14-2015, 11:19 AM. Reason: addition
  • budm
    Badcaps Legend
    • Feb 2010
    • 40746
    • USA

    #2
    Re: Proscan 42LA45H PSU Problem

    Can we see the pictures of the whole board, top and bottom side of the board, and also the pictures of the whole back side of the TV so we can see all the boards and how they are connected together?
    Also need the pictures of the connectors so I can see all the pin labels.

    http://www.shopjimmy.com/proscan-114...wer-supply.htm
    Last edited by budm; 10-14-2015, 12:15 PM.
    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

    Comment

    • CapLeaker
      Leaking Member
      • Dec 2014
      • 7972
      • Canada

      #3
      Re: Proscan 42LA45H PSU Problem

      sounds like your mainboard isn't returning PSon to the power supply. So the power supply doesn't turn on.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Proscan 42LA45H PSU Problem

        gnd - 0
        gnd - 0
        sw - 4.24v = PS-ON
        sw5 - 4.96v = 5VSTBY
        sw5 - 4.96v[/B] = 5VSTBY
        12/5 - 0.12v = SWITCHED 12V
        12/5 - 0.12v = SWITCHED 12V
        gnd - 0
        br? - 0 = DIM CTRL
        on - 0 = BL-ON
        gnd - 0
        gnd - 0
        m5v - 0.01v = SWITCHED 5V
        m5v - 0.01v = SWITCHED 5V
        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

        Comment

        • Nr1Ctr
          Member
          • Oct 2015
          • 22
          • USA

          #5
          Re: Proscan 42LA45H PSU Problem

          More pictures as requested. It'll be a couple hours before I'm back on here. Taking an Assembly Language class (one among many) and I've got a test today. I'll try and check on my phone. Thanks again

          Took me 30 minutes to upload the pics, lol. Hope you don't need many more.
          Attached Files

          Comment

          • budm
            Badcaps Legend
            • Feb 2010
            • 40746
            • USA

            #6
            Re: Proscan 42LA45H PSU Problem

            Thanks for the pictures, I may need more pictures of the bottom side if I cannot trace out the circuits, I'll let you know.
            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

            Comment

            • Nr1Ctr
              Member
              • Oct 2015
              • 22
              • USA

              #7
              Re: Proscan 42LA45H PSU Problem

              Alright then. Back in a bit. Test time..

              Comment

              • CapLeaker
                Leaking Member
                • Dec 2014
                • 7972
                • Canada

                #8
                Re: Proscan 42LA45H PSU Problem

                I guess I better go back to bed.

                Comment

                • Nr1Ctr
                  Member
                  • Oct 2015
                  • 22
                  • USA

                  #9
                  Re: Proscan 42LA45H PSU Problem

                  Back now. I like assembly. Only problem is that for every line you write in C++ you have to write 10 (or 100) in assembly. Will be here for a few hours now if anyone has some idea of where I should go from here.

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: Proscan 42LA45H PSU Problem

                    OK, I need 4 pictures (1 pictures of large red box, and then 3 sections of the bottom half of the board) total that are clear and without the glare because I cannot easily see the traces. Please do as close focused as you can.
                    Attached Files
                    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

                    Comment

                    • Nr1Ctr
                      Member
                      • Oct 2015
                      • 22
                      • USA

                      #11
                      Re: Proscan 42LA45H PSU Problem

                      Ok. Will get em first thing in the morning. I can email you the pic from my phone if you want. It's much higher quality and a lot easier to see the traces.

                      Comment

                      • Nr1Ctr
                        Member
                        • Oct 2015
                        • 22
                        • USA

                        #12
                        Re: Proscan 42LA45H PSU Problem

                        Here's the better pics. I took 4 instead of 3 going across from left to right. And a zoom in of the box you outlined. Hope you can get better visualization. My camera was having a hard time focusing but with more light it gave the glare again.
                        Attached Files

                        Comment

                        • Nr1Ctr
                          Member
                          • Oct 2015
                          • 22
                          • USA

                          #13
                          Re: Proscan 42LA45H PSU Problem

                          Are these good or do I need to get clearer ones?

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #14
                            Re: Proscan 42LA45H PSU Problem

                            I am downloading them right now.
                            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

                            Comment

                            • CapLeaker
                              Leaking Member
                              • Dec 2014
                              • 7972
                              • Canada

                              #15
                              Re: Proscan 42LA45H PSU Problem

                              Originally posted by budm
                              gnd - 0
                              gnd - 0
                              sw - 4.24v = PS-ON
                              sw5 - 4.96v = 5VSTBY
                              sw5 - 4.96v[/B] = 5VSTBY
                              12/5 - 0.12v = SWITCHED 12V
                              12/5 - 0.12v = SWITCHED 12V
                              gnd - 0
                              br? - 0 = DIM CTRL
                              on - 0 = BL-ON
                              gnd - 0
                              gnd - 0
                              m5v - 0.01v = SWITCHED 5V
                              m5v - 0.01v = SWITCHED 5V
                              Was sick yesterday
                              Last edited by CapLeaker; 10-15-2015, 05:12 PM.

                              Comment

                              • budm
                                Badcaps Legend
                                • Feb 2010
                                • 40746
                                • USA

                                #16
                                Re: Proscan 42LA45H PSU Problem

                                OK, please see the attached picture, we will need to get P/N of the M5V switch and the 12/5V SMPS IC, and Voltage at VCC2.
                                Check the DCV on all 3 pins of the M5V switcher.
                                PS-ON is present but it is not turning on the M5V switch and the 12/5 SMPS.
                                Attached Files
                                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

                                Comment

                                • Nr1Ctr
                                  Member
                                  • Oct 2015
                                  • 22
                                  • USA

                                  #17
                                  Re: Proscan 42LA45H PSU Problem

                                  Ok. I will have to figure out how I can hook it up to power and still get access to the back of the board. Will let you know what I find. Thanks again!

                                  Comment

                                  • budm
                                    Badcaps Legend
                                    • Feb 2010
                                    • 40746
                                    • USA

                                    #18
                                    Re: Proscan 42LA45H PSU Problem

                                    At least give us the P/N of those two devices so we can look up the spec sheet for them.
                                    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

                                    Comment

                                    • Nr1Ctr
                                      Member
                                      • Oct 2015
                                      • 22
                                      • USA

                                      #19
                                      Re: Proscan 42LA45H PSU Problem

                                      Here are pics of the two in question. Will get back to you about the voltage soon as I figure out how to get it without zapping myself.
                                      Attached Files

                                      Comment

                                      • Nr1Ctr
                                        Member
                                        • Oct 2015
                                        • 22
                                        • USA

                                        #20
                                        Re: Proscan 42LA45H PSU Problem

                                        Does it just need the AC power hooked up or do I have to make sure all the ribbon cables are connected?

                                        Comment

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