Polaroid P40LCD12

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Daveatfernie
    Senior Member
    • Nov 2013
    • 70
    • UK

    #21
    Re: Polaroid P40LCD12

    Tried forcing the psu in with the mainboard removed using a 470 ohm resistor but this was unable to start it either. (Connecting between 5v and power on input).
    Still nothing other than 3.3 and 5v. The mainboard seems to be not trying to power the psu up.
    The sw-switch input varies (sits at 5 when the mainboard is unplugged but raises to 7 with it connected). I'm unsure what this does and haven't traced it through the schematic yet.

    I was thinking of trying to bastardise one of my other tv psus to power the board to see if it will fire it up. It's a shame there isn't a standard cable arrangement between psus. Until I can rule out the psu I'm at a loss to be honest as to where to have at.

    I'll try the short between st_by and 5v tomorrow instead of the 470 ohm to see if there's any difference.

    It also seems strange that if the mainboard is at fault(a psu on board the mainboard for example) that the indicator led isn't flashing (as the service manual indicates it should) there is no illumination at all on the power led.

    Comment

    • vinceroger69
      Badcaps Legend
      • Mar 2012
      • 6714
      • uk

      #22
      Re: Polaroid P40LCD12

      ive had bad mainboards cause no power led dont rule it out. maybe budm or tom when there on maybe able to advise which pins to jump on the psu to check the other voltages etc.

      Comment

      • Daveatfernie
        Senior Member
        • Nov 2013
        • 70
        • UK

        #23
        Re: Polaroid P40LCD12

        That's what I was thinking with the LED not being illuminated.
        Ill try the psu shorting again, if there's no joy I'll start by getting a new psu.
        If I can get the psu to fire up I'll get a mainboard.

        Thanks again for all your help.

        Comment

        • CapLeaker
          Leaking Member
          • Dec 2014
          • 7972
          • Canada

          #24
          Re: Polaroid P40LCD12

          Here is the schematic on the power supply.
          On PL816 (a 28pin plug) measure the voltages of each pin and report back.
          Attached Files

          Comment

          • nomoresonys
            Badcaps Legend
            • Jan 2013
            • 12076
            • U.S.

            #25
            Re: Polaroid P40LCD12

            so many unsolved mysteries, I'm guessing the power supply swap fixed it?

            Comment

            • AFajitas
              Senior Member
              • Dec 2014
              • 183
              • USA

              #26
              Re: Polaroid P40LCD12

              [ATTACH]103243[/ATTACH]

              Comment

              • sweeney1987
                New Member
                • Nov 2015
                • 4
                • Ireland

                #27
                Re: Polaroid P40LCD12

                Did you ever find out if it was bad power board or main board, have same tv with exact same symptoms
                would help greatly if you told me.

                Searching there is a repair kit for these vestal psus, would that be fault?

                Comment

                • ReeceyBurger123
                  Never Give Up !
                  • May 2014
                  • 7325
                  • Britain

                  #28
                  Re: Polaroid P40LCD12

                  Checked D893 ?
                  Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                  https://www.facebook.com/Telford-Tel...7894576335359/

                  Comment

                  • sweeney1987
                    New Member
                    • Nov 2015
                    • 4
                    • Ireland

                    #29
                    Re: Polaroid P40LCD12

                    Originally posted by ReeceyBurger123
                    Checked D893 ?
                    Yes and gettin .47 of a drop from both it and D901

                    On further inspection there is a slight burn mark arond leg of D882 (anode side)
                    It and D883 are giving me readings both directions indicating theyre shorted
                    will try swapping them out first, thanks

                    Comment

                    • ReeceyBurger123
                      Never Give Up !
                      • May 2014
                      • 7325
                      • Britain

                      #30
                      Re: Polaroid P40LCD12

                      I have seen D882 or the one next to it go leaky in the past, they don't fully short but go leaky. The part on them in Mur460ax. Remove them off the board and check for leakage current sounds like the failure if the Pcb around them is burning also.
                      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

                      https://www.facebook.com/Telford-Tel...7894576335359/

                      Comment

                      Related Topics

                      Collapse

                      • Mirenia
                        Dell Latitude 7420 - Touchscreen not working since Mainboard replacement
                        by Mirenia
                        Hi everyone,

                        I've got a little "problem child": my Dell Latitude 7420 2-in-1, which had a faulty mainboard.
                        I replaced it, but ever since, the touchscreen no longer works — and honestly, I’m running out of ideas…

                        In Windows Device Manager, I just see an I2C HID Device with error code 10. Sporadically, the touchscreen is recognized correctly for just a few seconds, but I haven’t been able to determine under which circumstances this happens.

                        The touchscreen also doesn’t work in UEFI/BIOS, although it’s enabled...
                        03-30-2025, 06:47 AM
                      • orcic
                        MASTER TL240 and new mainboard LW36BKC01
                        by orcic
                        Hello,
                        I have an old MASTER TL-240 LED TV. Since it stopped working and it had a DVB-T receiver that is being dismissed in Italy, I've decided to replace the mainboard with a DVB-T2 one.
                        The original problem was that when switching on the TV, the power LED was transitioning from red to steady blue, without showing video or audio.
                        After checking some voltages on the power supply board (HKL-240101-B Rev. 1.4, HKL from now on) someone suggested me to replace the mainboard.
                        Now I have some doubts about how to connect the new mainboard to the old power supply.
                        First of...
                        05-12-2023, 08:10 AM
                      • Devonavar
                        Vizio M43-C1 - How closely do I need to match the mainboard number?
                        by Devonavar
                        I have a Vizio M43-C1 stuck in a reboot loop with no backlight.

                        I've tested all the voltage rails coming out of the power supply and they are "normal" for this model (PS_ON & DIM go high when turned on, BL_ON & 3D_ON are close to zero due to backlight power flowing through the mainboard, 5VSB is 5V, and 12V is 19V, which is apparently normal for this board).

                        Basically, I get similar results to Garry in this post: https://www.badcaps.net/forum/showthread.php?t=80346

                        So, I've ruled out the PSU for now.

                        The reboot loop...
                        08-14-2022, 08:46 PM
                      • l0lhaxz1
                        QN65QN90A - Mainboard MLCC failed - now bootloop
                        by l0lhaxz1
                        Hi

                        I have a QN65QN90A which was purchased around launch I guess making it about 1.5-2 years old... had been working fine until a few days ago, simply went black and would no longer turn on (at all). No standby light and no typical PSU relay click etc. Absolutely dead.

                        Pulled it apart without doing much research first, suspecting the power supply as it had a faint buzz (I guess due to the forthcoming found short), investigated PSU for some time and concluded there was no fault that I could spot with the board removed.

                        Came to learn after a bit more research...
                        02-06-2023, 08:59 AM
                      • Jembang
                        coocaa 50S5G smart tv dropped voltage when connecting power supply to mainboard
                        by Jembang
                        good day hoping someone can lend a hand, im repairing smart tv 50 inch, status when turning on back light is dim but you can see the tv logo then slowly fading out to black, i check the supply to tcon, i only read 5+v, must be 12v, i removed lvds cable and check voltage to mainboard turned on its also 5v, then i remove the cable mainboard to power supply, i read 12v in power supply, thinking that the problem is in the mainboard, coz theres 12v in power supply, i also check while turning on checking volts in main board 12v dropping to 5v, im just new repairing in TV, hope someone see my post t...
                        11-01-2024, 09:55 AM
                      • Loading...
                      • No more items.
                      Working...