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Current / voltage injection don’t work for me.

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    #21
    Re: Current / voltage injection don't work for me.

    Yes but if it does have a component short you should be able to find where it is getting hot because what I have been reading in post is not making sense
    9 PC LCD Monitor
    6 LCD Flat Screen TV
    30 Desk Top Switching Power Supply
    10 Battery Charger Switching Power Supply for Power Tool
    6 18v Lithium Battery Power Boards for Tool Battery Packs
    1 XBox 360 Switching Power Supply and M Board
    25 Servo Drives 220/460 3 Phase
    6 De-soldering Station Switching Power Supply 1 Power Supply
    1 Dell Mother Board
    15 Computer Power Supply
    1 HP Printer Supply & Control Board * lighting finished it *


    These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

    1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
    2 Hem Saw Computer Stack Board

    All of these had CAPs POOF
    All of the mosfet that are taken out by bad caps

    Comment


      #22
      Re: Current / voltage injection don't work for me.

      Thanks, so, I’m not crazy. Something should happen. I supposed an issue from PSU, and I measured 5A and 3,3v (while injecting) and wire was hot, so PSU is good.
      Maybe I works in a room too cold (14-15 degre C) ? I will try soon to preheat card to 30-40 regree for help the heat to emerge of the board.

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        #23
        Re: Current / voltage injection don't work for me.

        It would help if you had component freeze spray and freeze the components one at a time and the one that you see get rid of the ice that formed on the top of the component is probably the one that is the issue

        One note you should be careful about injecting power on a power supply rail this can screw up the voltage monitoring system ic chip because I had it happen to me once and now only do this as a last resort and probably remove the monitoring ic chip first before I would inject power into the power supply rail just food for thought

        I hope this helps you
        Last edited by sam_sam_sam; 01-01-2022, 10:56 AM.
        9 PC LCD Monitor
        6 LCD Flat Screen TV
        30 Desk Top Switching Power Supply
        10 Battery Charger Switching Power Supply for Power Tool
        6 18v Lithium Battery Power Boards for Tool Battery Packs
        1 XBox 360 Switching Power Supply and M Board
        25 Servo Drives 220/460 3 Phase
        6 De-soldering Station Switching Power Supply 1 Power Supply
        1 Dell Mother Board
        15 Computer Power Supply
        1 HP Printer Supply & Control Board * lighting finished it *


        These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

        1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
        2 Hem Saw Computer Stack Board

        All of these had CAPs POOF
        All of the mosfet that are taken out by bad caps

        Comment


          #24
          Re: Current / voltage injection don't work for me.

          Originally posted by corrize View Post
          If I inject 20A in the shorted line, the short take all current first until it burn.
          Aren't you looking for a faulty component? If it burns out what's the problem since it was faulty to begin with.
          Originally posted by sam_sam_sam View Post
          (...) component short you should be able to find where it is getting hot because what I have been reading in post is not making sense
          Neither to me...!
          Originally posted by corrize View Post
          Thanks, so, I'm not crazy.
          It was never my intention, neither i did it. Just want to help.

          Take all the advises given previously and go for it...

          Comment


            #25
            Re: Current / voltage injection don't work for me.

            If you are injecting power let’s say 3v for a 3v rail at 5A and nothing gets hot, the answer is something is getting heatsinked very well. So it’s not a small SMD cap that’s shorted, as it would get really hot at that current.

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              #26
              Re: Current / voltage injection don't work for me.

              Ha thanks, that’s I wanted to know, that’s could not be a small component at such power. Indeed, I put my lips everywhere on this board (I did not put the tongue !) so, if a small component was shorted, I would have burned. ok
              So, the short is probably between BGA balls, under chipset, that could explain why even the chipset kept cold. I will try to check that.

              Comment


                #27
                Re: Current / voltage injection don't work for me.

                A Leakseeker 89 would really handy in this case or a Ohm meter that can read very low like a mili Ohm. So now you know roughly what to look for you can isolate sections of that rail and start taking a few things of the board and hopefully find that bugger.
                It could be anything that looks like an IC. It must be something bigger, maybe even something that has its belly grounded to the PCB itself like a mosfet.

                Comment


                  #28
                  Re: Current / voltage injection don't work for me.

                  Hello
                  how to set this in QW-MS305D device 1V 3A?

                  Thank you

                  Comment


                    #29
                    Re: Current / voltage injection don't work for me.

                    I've had some success finding shorted components using a milli-ohm meter.
                    Mine is a model VC480C+ and it wasn't terribly expensive.
                    The only downside is that this method may require a schematic more so than looking for the hot spot.

                    Comment


                      #30
                      Originally posted by corrize View Post
                      Hello, I recently use PSU for voltage injection. I sent 1.2v 5A ... 1.5v 5A and I felt nothing again. Probably CPU/chipset dead because caps at reverse side are shorted to ground (0 Ohms) but I felt no warm. I used thermal probe and temps grew up for 4 degree C. Low for 7.5W ?

                      What's happen ? My PSU is bad ? Wich values do you use for voltage injection pls ?
                      What happen? First, you should know that for inject "voltage" is using linear psu, not switching generally, because some switching psu has flanzy protection that trigered with shorts. But, you write that your wire get hot, so that it not case...

                      When you SET UP psu to 1.5v 5A, you just set the limit which you use in testing, so that do not mean that you will use that power. 7.5w is easely detectet if is in spot on faulty component, but if you connect setted psu on short circuit of 0 ohm... you will drop voltage near zerro and results with no significiant heat disipation, say 0.01v x 5A is produce little heat that is not easy to detect.

                      Always run this mathematics in brain background so you know what to expect.
                      Second, you dont mentioned voltage drop you have, but only what you set. From there you can know directly with what resistance you deal (1R=1V, 0.001R=0.001V in 1A cc)

                      Comment

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