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Westinghouse SK-32H540S

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    #1

    Westinghouse SK-32H540S

    HI, since people here are stumped on my Haier question I will ask about my Westinghouse SK-32H540S. I received this tv dead as in no power light or sound or anything. The person before me attempted a fix and seen the center transformer on the board was burnt and so was the board so that was replaced. So far I have pulled out the 3 big transformers and compared readings to each other and they seem very close. I also pulled the electrolytic capacitors out and checked them with my Atlas ESR70 and all passed (none looked bulged either) I pulled out the mosfets and checked those also and were ok except for the 2 I have circled in the pic which looks to have diodes as part of one leg and I'm uncertain on how to check them. I also tested the large resistors and diodes on top and seem ok. Next I looked at the solder connections under lighted magnification and touched up anything that looked remotely like something. So after all that I'm stuck.
    Attached Files
    Last edited by CraigR; 12-15-2013, 01:09 PM.
    Tags: None
    #2
    Re: Westinghouse SK-32H540S

    Hi,
    Just throwing some questions here
    All fuses are ok?
    Does voltage reaches the rectifier bridge/main filter caps?
    Is voltage present at the 5 V standby driver IC?
    Any standby voltage output?
    Does the maind board sends the PS_On ?
    In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

    Comment

      #3
      Re: Westinghouse SK-32H540S

      Sorry forgot to mention Yes, power through the fuse and on the low side I have all the correct voltages coming out as printed next to the connector 5v 12v etc...

      Comment

        #4
        Re: Westinghouse SK-32H540S

        Well, if all voltages are correct (5V, 5Vs and 12V), then regardless of any problem on the inverter side, you should have some activity on the LED (standby light, blinking).
        Is there any voltage on the BL_On pin ?
        In this case verify also the voltages on the main board regulators.
        In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

        Comment

          #5
          Re: Westinghouse SK-32H540S

          Might be on to something, no voltage at BL_ON pin. Not sure how to check voltage on mainboard regulators.

          Comment

            #6
            Re: Westinghouse SK-32H540S

            Well, best if you see it yourself (than a long description)
            Search Youtube for main board voltage regulator test, or:
            http://www.youtube.com/watch?v=cNFzBJELFoU
            In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

            Comment

              #7
              Re: Westinghouse SK-32H540S

              Do I even need to check the main board now that there is no BL_ON voltage?

              Comment

                #8
                Re: Westinghouse SK-32H540S

                BL_on IS coming from the main board ! (it is the Backlight On command/voltage, so the inverter can start)!
                In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                Comment

                  #9
                  Re: Westinghouse SK-32H540S

                  Ok will watch video and get back after testing. Here also is a pic of the main board.
                  Attached Files

                  Comment

                    #10
                    Re: Westinghouse SK-32H540S

                    Read similar threads:

                    https://www.badcaps.net/forum/showthread.php?t=21240
                    https://www.badcaps.net/forum/showthread.php?t=22440
                    In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                    Comment

                      #11
                      Re: Westinghouse SK-32H540S

                      Ok, I think I did this correct. Here is a pic with the voltages and where I got them. Also read those threads before posting the first time.
                      Attached Files
                      Last edited by CraigR; 12-15-2013, 02:35 PM.

                      Comment

                        #12
                        Re: Westinghouse SK-32H540S

                        This is another story :P

                        IC206 is ok, 5V on it's output as it should;
                        Q201 is probably a transistor, not a voltage reg;
                        What voltage is on middle pin IC202 (should be 3,3V)?
                        Deafinetly a problem on IC712 (what is the marking on it?) - has input, but no output!!
                        Question mark on IC711, but i see no input voltage on pin 3 (what is the marking on it?)?
                        In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                        Comment

                          #13
                          Re: Westinghouse SK-32H540S

                          3.28v on the middle leg.
                          and on IC712 I double checked volt and what I have is correct. On the chip is J355 and under it is 1117-33
                          The marking on IC711 is K051 and under that is 1117-18

                          Comment

                            #14
                            Re: Westinghouse SK-32H540S

                            Right, 3,28V it is correct!
                            IC712 is also a 3.3V regulator, and 99% faulty!
                            IC711 is a 1.8V regulator, and I belive that it's taking the 3.3V from IC712 as input (but since IC711 has a problem the voltage never reaches the input) so it might be ok.
                            Next step would be to replace the IC7111, 3.3V regulator and post the results !

                            All the best
                            In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                            Comment

                              #15
                              Re: Westinghouse SK-32H540S

                              Correction - replace IC712
                              In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                              Comment

                                #16
                                Re: Westinghouse SK-32H540S

                                Thank you so much for the help. Any suggestion where to get one? Thanks again!

                                Comment

                                  #17
                                  Re: Westinghouse SK-32H540S

                                  http://www.digikey.com/product-searc...=0&pageSize=25

                                  http://ro.mouser.com/ProductDetail/S...WdNxB93SNXjw2a

                                  Or try from salvage boards, they are quite common!
                                  In a transistor circuit protected by a fuse, the transistor will always blow to protect the fuse.

                                  Comment

                                    #18
                                    Re: Westinghouse SK-32H540S

                                    Well got the part from mouser in your link and put it in and still dead.

                                    Comment

                                      #19
                                      Re: Westinghouse SK-32H540S

                                      Ok - Can you test test the new VR to see what voltage it gives?

                                      Retest the others as well.
                                      Last edited by selldoor; 12-27-2013, 11:17 AM.
                                      Please upload pictures using attachment function when ask for help on the repair
                                      http://www.badcaps.net/forum/showthread.php?t=39740

                                      Comment

                                        #20
                                        Re: Westinghouse SK-32H540S

                                        did the voltages on the regulator alter with the new part or is it the same as before?

                                        Comment

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