17MB35-4 3.3V Shorted Help ?

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

    #1

    17MB35-4 3.3V Shorted Help ?

    Hello all, I have here a 32" Lowry Tv rebadged Vestel junker. The failure here is that the standby led comes on red (standby) then goes blue (on) then shuts down back to red, what is happening is the Psu is going into over load because the mainboard is shorted. I had one of these 17MB35-4 with the same failure and never fixed it. The whole 3.3 volt section is almost completely shorted to ground very little ohms, this is abnormal. Here is what I found:

    U121 Reg shorted in circuit however tests fine out of circuit.
    U132 Reg shorted in circuit however tests fine out of circuit.
    C308
    C293
    C290
    C284 Ceramic capacitors all show shorted in circuit however test fine out of circuit.
    All fuses are good, which isnt good because it means that the fuse has failed to protect the circuit hence Psu going into shitdown.

    I cant seem to fond what part the voltage stops at as it shuts down too fast. Any help or ideas on what to test are greatly appreciated. Thank you.
    Last edited by ReeceyBurger123; 10-18-2015, 04:16 PM.
    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 !

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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: 17MB35-4 3.3V Shorted Help ?

    Have you replaced the PSU? What model PSU is it?

    I bet I know what the problem is (it's got 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

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

      #3
      Re: 17MB35-4 3.3V Shorted Help ?

      Hi mate, the Psu I dont think was replaced however the guy has had the back off its a 17PW26-4 Supply. It surely cant be the Psu as I have swapped these around with the same main board before and again had the same failure months back on the same board on a 42" Hitachi which was never opened, the 3.3v section shorted on that :L
      Last edited by ReeceyBurger123; 10-18-2015, 04:19 PM.
      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

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: 17MB35-4 3.3V Shorted Help ?

        If the wrong power board is installed 5V & 3.3V will be shorted at the power board causing a blinking LED and failure to power up. Usually does not cause damage despite 3.3V rail being at 5V (protection circuit catches the fault quickly, which is nice of Vestel I suppose.)

        You need to remove a jumper between 5V & 3.3V on the power board. It's a small surface mount zero ohm link. I can't remember the part number but it's right next to the connector.
        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

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

          #5
          Re: 17MB35-4 3.3V Shorted Help ?

          Tom, the 3.3v rail going to the mainboard is shorted to ground 5v is fine. I am 90% sure its not the Psu that caused this.
          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/

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          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: 17MB35-4 3.3V Shorted Help ?

            OK, didn't realise it was a ground short. If 3.3V is shorted to ground then it is probably a bad CPU or other component like HDMI receiver shorted. Not an easy fix.

            You can try powering 3.3V using an external PSU and seeing what gets hot but otherwise you're probably going to need a new main board.

            Maybe you'll find a shorted MLCC. I had one of the 17MB62 boards with about 5 ohms between 3.3V and ground, I believe it was power surge damage on HDMI input but may also have been a random CPU failure.
            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

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

              #7
              Re: 17MB35-4 3.3V Shorted Help ?

              Hmm thanks for the info Tom Going to try that tomorrow, will put 3.3v into the this I think you might be right as the lowest point of resistance seems to be from the Hdmi processor 22 ohms to ground on the 3.3v input to it which isnt normal.
              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/

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

                #8
                Re: 17MB35-4 3.3V Shorted Help ?

                Quite certain that the Hdmi processor is at fault now, not only is there super low ohmage it almost looks like there is a blister in the centre of it :L Hmm going to look into this more tomorrow. Already had enough of Hdmi chips today after fixing a Panasonic with a Hdmi processor related issue earlier. Will update you tomorrow on what I find.
                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 !

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                • stj
                  Great Sage 齊天大聖
                  • Dec 2009
                  • 30977
                  • Albion

                  #9
                  Re: 17MB35-4 3.3V Shorted Help ?

                  i had this, it took forever to find.
                  it was a shorted ceramic cap.

                  Comment

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

                    #10
                    Re: 17MB35-4 3.3V Shorted Help ?

                    Cheers Stj do you remember the part number ?
                    Last edited by ReeceyBurger123; 10-18-2015, 04:53 PM.
                    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/

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

                      #11
                      Re: 17MB35-4 3.3V Shorted Help ?

                      Also that Hdmi chip is not the lowest point of resistance there is a ceramic cap checking lower however out of circuit it checks fine, but sort of happy I can nearly rule that Hdmi processor as not being the issue. Stj do you remember the part number of that cap cheers ?
                      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/

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

                        #12
                        Re: 17MB35-4 3.3V Shorted Help ?

                        Here is an image of this board, I know its crappy contrasts however just sent if you could highlight or tell me where that bad MLCC was cheers.
                        Attached Files
                        Last edited by ReeceyBurger123; 10-18-2015, 05:07 PM.
                        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

                        • stj
                          Great Sage 齊天大聖
                          • Dec 2009
                          • 30977
                          • Albion

                          #13
                          Re: 17MB35-4 3.3V Shorted Help ?

                          that's a different layout, but it would be in the psu section lower-left in your foto.
                          strangely yours seems to be missing most of the parts!

                          i will tell you how i foud it.
                          i made a list of all the caps on the 3v3 rail,
                          then i hooked my meter to the 3v3 and gnd set to continuity with the beeper on.

                          then i just lifted and put back each part with the air-station till the meter stopped beeping.
                          and that's why it takes forever!

                          Comment

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

                            #14
                            Re: 17MB35-4 3.3V Shorted Help ?

                            Nice one cheers Stj
                            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/

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                            • wills123
                              Senior Member
                              • Jan 2014
                              • 72
                              • england

                              #15
                              Re: 17MB35-4 3.3V Shorted Help ?

                              Not sure if it helps but I used to fault find xbox360 shorts by jumping a pc psu always on then jumper wire affected rail and either smoke or very hot component usually made it fast to find problem

                              Comment

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

                                #16
                                Re: 17MB35-4 3.3V Shorted Help ?

                                Cheers Wills going to do that now This thing is bumming me out as removed every single MLCC and all test fine so something else is up hmm time to keep diagnosing.
                                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

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

                                  #17
                                  Re: 17MB35-4 3.3V Shorted Help ?

                                  Well wouldn't you know it would be the last thing I checked, the flipping Hdmi processor is at fault, didn't even need an external psu to determine that this thing was getting very very hot, it burnt my finger haha. I removed the processor off the Pcb and the tv now behaves normally. The Psu completes its self test and the short on the 3.3v rail has gone, upon pressing the power button the standby light goes blue but after about 10 seconds the tv shuts down this is because the Cpu is detecting that the Hdmi chip is not present.

                                  Now time to try and find this:
                                  Sil9185AC1U
                                  0951
                                  AG03KX2
                                  Last edited by ReeceyBurger123; 10-19-2015, 01:07 PM.
                                  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

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

                                    #18
                                    Re: 17MB35-4 3.3V Shorted Help ?

                                    Found one for £3
                                    http://www.ebay.co.uk/itm/1-Piece-SI...-/400331089328
                                    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

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

                                      #19
                                      Re: 17MB35-4 3.3V Shorted Help ?

                                      Now I know before any one says its a difficult solder job, I have been able to replace a scan Ic with success which has a lot more pins so think I should be able to do this. Going to order an Ic and let you all know thanks chaps
                                      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

                                      • stj
                                        Great Sage 齊天大聖
                                        • Dec 2009
                                        • 30977
                                        • Albion

                                        #20
                                        Re: 17MB35-4 3.3V Shorted Help ?

                                        does it have a pad under it?

                                        Comment

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