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    #61
    Re: Testing VRMs

    Originally posted by bianchi77 View Post
    I've found two missmatch value with the code written on it..05A = 110 ohm...measured in circuit 66 ohm...
    09A = 121 ohm....measured in circuit 67 ohm....and they are not in parallel...

    Could it be the problem ?
    Or this one :
    I do not know what you are referring too, resistors or capacitors. We were dealing with the caps, now you are talking about the resistor values?
    09A, 05A are for the resistors.
    Last edited by budm; 09-14-2016, 10:55 AM.
    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


      #62
      Re: Testing VRMs

      Originally posted by budm View Post
      I do not know what you are referring too, resistors or capacitors. We were dealing with the caps, now you are talking about the resistor values?
      09A, 05A are for the resistors.
      Yes we are talking about capacitors, but I'm testing the resistors as well near the capacitors while I'm there, curiousity....

      I'll let you know the resistance value of the capacitors I've taken from the bottom of the CPU...

      Comment


        #63
        Re: Testing VRMs

        https://www.badcaps.net/forum/attach...5&d=1473809915
        Why don't you concentrate on that section first in the diagram instead of moving to another section?
        Where does the output of that section go to?
        The low resistance still there ON THE OUTPUT CAPS if you lift L2, L3?
        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


          #64
          Re: Testing VRMs

          because there's no short to the ground from that section....with the value 35 ohms without CPU...

          yes the low resistance is still there when I remove L2 and L3....
          the output is going to the CPU....that section is taken from datasheet so it's not exactly the same with the board....but that's the chip on the board...

          I can't measure the resistance of those capacitors with CPU since it's on the bottom of the CPU...

          Comment


            #65
            Re: Testing VRMs

            L2 and L3 are filter output of Vcore for CPU...

            Comment


              #66
              Re: Testing VRMs

              So you are getting 9 Ohms when CPU is installed and 35 Ohms when CPU is removed?
              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


                #67
                Re: Testing VRMs

                Originally posted by bianchi77 View Post
                L2 and L3 are filter output of Vcore for CPU...
                Lifting the inductors Lx is to isolate the output section of the power supply from the load to find out if the low resistance is from the power supply or from the loads.
                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


                  #68
                  Re: Testing VRMs

                  yes 35 ohm without CPU.....now 35 ohm only from those small capacitors below the CPU...
                  do you reckon one or some of them are faulty ? because from my experience...ceramic capacitor never give me a very low resistance....

                  Have you got one before with SMD MLCC faulty ? overvoltage and overheat from the CPU I reckon ....

                  Comment


                    #69
                    Re: Testing VRMs

                    BTW, you never tell us what dcv you were getting at the output of that power supply.
                    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


                      #70
                      Re: Testing VRMs

                      cearamic capacitor never give me a very low resistance: when they fail they will short out or have very low resistance. MLCC cracked easily.
                      Attached Files
                      Last edited by budm; 09-14-2016, 07:16 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


                        #71
                        Re: Testing VRMs

                        BTW, do you other mother board that you can check the resistance of the Vcore and GND?
                        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


                          #72
                          Re: Testing VRMs

                          From 7 caps I have taken off....value = 5uF and resistance is on level M ohm until OL...
                          which normal....character of charging of capacitor...I have another 16 to 18 caps to analyze now...hmm...abit fiddly...small on the bottom of the CPU....

                          Comment


                            #73
                            Re: Testing VRMs

                            34.5 ohm photo....without cpu 34.5 ~ 35 ohm....don't worry it's nearly the same...
                            Attached Files

                            Comment


                              #74
                              Re: Testing VRMs

                              I measured from other working motherboard...even lower from Vcore to ground = 2.1 ohm with CPU....

                              I have a doubt if it's ceramic caps problem....I suspect I have problem with my buck controller....it's generating voltage more than the CPU needs and shut down...

                              Comment


                                #75
                                Re: Testing VRMs

                                I'm thinking for unsoldering NCP5322 and see what's the response without that chip...
                                another test...

                                Comment


                                  #76
                                  Re: Testing VRMs

                                  NCP5322 unsoldered...
                                  Attached Files
                                  Last edited by bianchi77; 09-14-2016, 10:25 PM.

                                  Comment


                                    #77
                                    Re: Testing VRMs

                                    I've tested just now without NCP5322 and CPU on it....it's running stable not suddenly off...all FETs,Caps and inductors on it....
                                    I'm waiting for my NCP5322 coming now....hopefully it will answer my question

                                    Comment


                                      #78
                                      Re: Testing VRMs

                                      Originally posted by budm View Post
                                      It should be very high in the K Ohms range because the devices (Loads) are not active.
                                      In my experience, CPUs and GPUs always measure low resistance, typically under 10 Ohms. So the reading bianchi77 got on the CPU output isn't indicative of anything wrong at all. Now, if he removes the CPU he *may* get a high resistance reading of a few hundred Ohms to a few KOhms, *IF* the Northbridge doesn't use CPU V_core for its power (which is the case only with only *a few* motherboards).

                                      Comment


                                        #79
                                        Re: Testing VRMs

                                        I removed CPU resistance to ground = 34.5 ohm...do you mean northbridge sharing the same Vcore ?

                                        Comment


                                          #80
                                          Re: Testing VRMs

                                          Originally posted by bianchi77 View Post
                                          Is it possible that one of the ceramic caps near the CPU is short ? ( on the bottom of the CPU, inside the socket )
                                          Possibly, although I have seen only a few short out with such a high resistance (34.6 Ohms without CPU in socket). Most go short-circuit like a piece of "wire" (i.e. sub-1 Ohm)

                                          Originally posted by bianchi77 View Post
                                          without CPU in socket, 34.6 ohm...
                                          Any thick traces going from CPU V_core to Northbridge? If yes, that means the NB is powered by CPU V_core as well, and that's what would be giving you the still-fairly-low resistance of 34.6 Ohms.

                                          Originally posted by bianchi77 View Post
                                          I have removed all the output capacitors now....I got only 8 ohms between Vcore and GND...CPU in socket...
                                          If you are trying to find a short-circuit on CPU VRM, *ALWAYS* remove the CPU from the socket. Otherwise the CPU will give you a low resistance reading and you will never know where the short-circuit is coming from.

                                          Originally posted by budm View Post
                                          Something does not make sense here, you had 9 Ohms before the output caps and MOSEFTs are removed, and now you have 7.7 Ohms, and 8 ohms?
                                          Could be his multimeter, if he is using a cheap one. I know my Harbor Freight meters will sometimes show 1 Ohm with shorted leads and other times up to 3 Ohms, depending if I don't play with the rotary dial.

                                          That's why I never take it for granted that anyone here is using perfect test equipment. Always watching out for "weird" and "off" measurements.

                                          Comment

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