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Asus MK241H no power

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    Asus MK241H no power

    I have picked up this monitor and it seems dead. No standby led, no standby voltage.
    The only voltage I can measure is the 170V on the big cap.
    I have found a bad FET transistor(Q101) which I have replaced and all the capacitors, just to be sure.
    What else can I check?
    I have made some pictures, they are not the best. I can make new ones tomorrow if needed.
    Attached Files

    #2
    Re: Asus MK241H no power

    Hi - I dont know how you can get pictures so good and pictures so bad in the same series. Anyway if you have 170Vdc at the big cap and nothing else. Id first check the
    voltages coming out of the transformer.
    On the pic of the back for the board bottom left just above the 16pin connector there is a component that looks to have
    A1 or 1V on it - is its a fuse - can you test it.
    Please upload pictures using attachment function when ask for help on the repair
    http://www.badcaps.net/forum/showthread.php?t=39740

    Comment


      #3
      Re: Asus MK241H no power

      The pictures made from above were done on a stand and the side onese from hand.
      The fuse checks out good. There are two more on the bottom, F101, F102 they are good too.

      Comment


        #4
        Re: Asus MK241H no power

        Q101 was shorted, correct? There may be other components shorted, preventing the power supply from starting. What is the part number for IC200 (located on bottom of board)? And is it connected to Q101?

        Comment


          #5
          Re: Asus MK241H no power

          It was shorted in every direction. Most likely you are right that is not only this Fet is out.
          I will check it when I will get home.

          Comment


            #6
            Re: Asus MK241H no power

            The IC is AS324AM-E1.

            Comment


              #7
              Re: Asus MK241H no power

              Originally posted by tibimakai View Post
              What else can I check?
              See if the SMPS IC is shorted between Vcc and GND.
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              Comment


                #8
                Re: Asus MK241H no power

                There is 75.5kohm, so I guess it's not shorted.

                Comment


                  #9
                  Re: Asus MK241H no power

                  As odd as it sounds, the AS324 is a quad op amp. Not what we're looking for. We're looking for the pwm controller that drives Q101. On the heatsink that Q101 is mounted on there's another device mounted to it on the opposite side. What's the part number of it?

                  Comment


                    #10
                    Re: Asus MK241H no power

                    K3568

                    Comment


                      #11
                      Re: Asus MK241H no power

                      Q101 has
                      G=0.040V
                      D=168V
                      S=0.045V
                      Q(otherside)(hooked up flipped over can't see the number right now)
                      G=0.068V
                      D=168V
                      S=0V

                      Comment


                        #12
                        Re: Asus MK241H no power

                        Not it either. Okay, on your fourth photo, there are two 8-legged chips towards the bottom. Looks like IC100 and IC102? How about their part numbers?
                        Last edited by jetadm123; 06-29-2012, 08:53 PM.

                        Comment


                          #13
                          Re: Asus MK241H no power

                          If I measure between pin 1 and pin 4 on A324, I'm not getting anything 0V.

                          Comment


                            #14
                            Re: Asus MK241H no power

                            There are two more ICs on the bottom:
                            EA1530A VCC=0V
                            L6562D VCC=0.133V
                            Last edited by tibimakai; 06-29-2012, 09:15 PM.

                            Comment


                              #15
                              Re: Asus MK241H no power

                              Originally posted by tibimakai View Post
                              There are two more ICs on the bottom:
                              EA1530A
                              L6562D
                              Great!

                              EA1530A is a TEA1530A power supply controller and the L6562D ia a power factor (PFC) controller.

                              You can test across pins 1 and 2 of the TEA1530 to test if Vcc and ground are shorted.

                              Test across pins 6 and 8 of the LD6562 to test Vcc and ground for a short.

                              At this point, I suspect pin 6 of the TEA1530 or pin 7 of the LD6562 are connected to the Gate of Q101. You can try using your meter to perform a continuity check to verify this. Sorry, but I must sign off for now. Hopefully, another member can take over.
                              Last edited by jetadm123; 06-29-2012, 09:24 PM.

                              Comment


                                #16
                                Re: Asus MK241H no power

                                OK, I look at the pictures, you will need to get the P/N on the SMPS and PFC IC.
                                Edited: OK, I see you got the P/N for the ICs.
                                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


                                  #17
                                  Re: Asus MK241H no power

                                  Found these two resistors suspect to me. The previuos owner mentioned about a pop before all went south.
                                  Attached Files
                                  Last edited by tibimakai; 06-29-2012, 09:32 PM.

                                  Comment


                                    #18
                                    Re: Asus MK241H no power

                                    They sure do look burnt up, cannot read the values any more, you will have to find out what pin of the IC they are connected to, then download the spec sheet of the IC to see what that pin/s do.
                                    Man! Good pictures? What camera do you use? Is it that USB Micro scope? I forgot the model number you gave me.
                                    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


                                      #19
                                      Re: Asus MK241H no power

                                      Forum is back and it's much more snappier, yeahh!
                                      The pictures are made with the USB Microscope. This one, which is 2MP:
                                      http://www.amazon.com/Celestron-Delu...usn+microscope
                                      The resistors are from pin #5. I can't find resistor values anywhere on the net.
                                      I have found some values from another Asus 19" monitor.
                                      The resistors still have a value, one is 180KOhm and the other is 2.5MOhm(this one I haven't removed yet, it may have other value removed).
                                      While the forum was down and I couldn't work on the monitors/TVs from the forum, I have fixed a LG L227WTG 22" monitor, and a Samsung 226BW 22" monitor, bad caps.
                                      Last edited by tibimakai; 07-03-2012, 12:49 AM.

                                      Comment


                                        #20
                                        Re: Asus MK241H no power

                                        Should I replace the resistors, or just leave them, since they have a value?
                                        The values that I have found in another service manual for a 17" monitor, had much smaller values(1K and 22K).
                                        I will just replace the EA1530A chip, it's cheap anyway and go from there.
                                        Last edited by tibimakai; 07-05-2012, 01:32 PM.

                                        Comment

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