Announcement

Collapse
No announcement yet.

Dell Latitude D520 AC Charger LED Turns Off When Plugged In

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Dell Latitude D520 AC Charger LED Turns Off When Plugged In

    I've checked the voltage on the charger, and it's a
    healthy +19.5V, but only when it's not plugged into
    the motherboard, which is now completely disassembled
    except for the memory. As soon as I plug it into the
    connector, the LED on the charger goes out, indicating
    short-circuit protection, and the laptop cannot be
    turned on. But when I probe for the short on the connector
    with my DMM, I cannot find the short....it's all high impedance.

    I also tried this with another, identical charger, and the
    same thing happens.


    #2
    Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

    Originally posted by Paul678 View Post
    I've checked the voltage on the charger, and it's a
    healthy +19.5V, but only when it's not plugged into
    the motherboard, which is now completely disassembled
    except for the memory. As soon as I plug it into the
    connector, the LED on the charger goes out, indicating
    short-circuit protection, and the laptop cannot be
    turned on. But when I probe for the short on the connector
    with my DMM, I cannot find the short....it's all high impedance.

    I also tried this with another, identical charger, and the
    same thing happens.

    ok, update:

    There is a short somewhere, but it's hard to
    figure out where, because it may be just one component
    on the power plane, which is making many MOSFETs
    and caps appearing to be shorted.

    I'm in the process of removing them one-by-one.

    Painstaking, yes, but I've got to give it a shot before
    I give up on this board.

    Sometimes you have to go into brute-force mode.....

    Comment


      #3
      Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

      Questions:

      1. is this an OEM brick?

      2. if so, is it a PA-10? PA-12? Other model?
      sigpic

      (Insert witty quote here)

      Comment


        #4
        Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

        Sometimes it is simpler to feed in 20V, current limited to 500mA or so (use a 39 ohm power resistor), and feel what component gets warm. The brute force way is to limit the current to 3A and see what smokes... wouldn't want to try that on a motherboard though!
        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


          #5
          Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

          Originally posted by tom66 View Post
          Sometimes it is simpler to feed in 20V, current limited to 500mA or so (use a 39 ohm power resistor), and feel what component gets warm. The brute force way is to limit the current to 3A and see what smokes... wouldn't want to try that on a motherboard though!
          I think the problem is with the brick (voltage source), not the laptop (voltage receiver). That wouldn't help.
          sigpic

          (Insert witty quote here)

          Comment


            #6
            Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

            Originally posted by ratdude747 View Post
            Questions:

            1. is this an OEM brick?

            2. if so, is it a PA-10? PA-12? Other model?
            Yes, these appear to be OEM.

            One is PA-10, the other is PA-12.

            Model # NADP-90kb and LA65NS1-00

            Comment


              #7
              Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

              Originally posted by ratdude747 View Post
              I think the problem is with the brick (voltage source), not the laptop (voltage receiver). That wouldn't help.
              But I tried 2 different voltage sources, and they both
              did the same thing. Also, there IS a short on the
              mother board, with MOSFETs reading a short both
              ways from drain to source, even after the gates have
              been shorted to ground. Also, nearby caps read short
              both ways as well, so something is up.

              To Tom: yes, I've already tried that. It kinda made the
              mosfets hot, so that's where I'm looking. I went up to
              about 2 amps, with my bench powersupply in current-limit
              mode, but if I get desperate, I'll try 3 amps! haha

              Comment


                #8
                Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                Update:

                Ok, I found a shorted N-channel MOSFET:



                Ordered 4 from Newark, because I absolutely hate how
                Mouser and Digikey don't tell you what the final shipping cost
                will be up front! $10 total.

                I know this was the problem, because after I removed it,
                I was able to plug the charger in, and the LED remains on.

                As usual, I'm bracing myself for something else to be
                wrong besides this one MOSFET, but hope springs eternal!!

                haha!

                Last edited by Paul678; 04-17-2012, 02:40 PM.

                Comment


                  #9
                  Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                  Originally posted by Paul678 View Post
                  Update:

                  Ok, I found a shorted N-channel MOSFET:



                  Ordered 4 from Newark, because I absolutely hate how
                  Mouser and Digikey don't tell you what the final shipping cost
                  will be up front! $10 total.

                  I know this was the problem, because after I removed it,
                  I was able to plug the charger in, and the LED remains on.

                  As usual, I'm bracing myself for something else to be
                  wrong besides this one MOSFET, but hope springs eternal!!

                  haha!

                  WORKS BABY!!!

                  It was just that one Mosfet!

                  I pretty much did this one myself, but thanks for
                  your inputs anyways!!!!

                  Comment


                    #10
                    Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                    Hey Paul678 first of all, congratulations on making it work . Please tell me the equipment you used to troubleshoot your board and the steps you took to fix it as I am in the same dilemma at the moment.

                    Comment


                      #11
                      Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                      Originally posted by Pacifist View Post
                      Hey Paul678 first of all, congratulations on making it work . Please tell me the equipment you used to troubleshoot your board and the steps you took to fix it as I am in the same dilemma at the moment.
                      You got one that turns the adapter LED off too? I have a Studio 1537 doing it and it's driving me spare would also love to know!

                      Think I might just start taking components out of the chain and seeing which lines are at fault.
                      Dell E7450 | i5-5300U | 16GB DDR3 | 256GB SSD

                      Comment


                        #12
                        Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                        Greetings,
                        This was the only post about this model so I am sending my request here.

                        First of all, does someone know where I can get the schematics for this laptop? Latitude D520

                        Moreover, this is the part I need to clarify what exactly is in order to buy and replace it. I am attaching a photo.

                        Thanks in advance all!
                        Attached Files

                        Comment


                          #13
                          Re: Dell Latitude D520 AC Charger LED Turns Off When Plugged In

                          Originally posted by mpikou View Post
                          Greetings,
                          This was the only post about this model so I am sending my request here.

                          First of all, does someone know where I can get the schematics for this laptop? Latitude D520

                          Moreover, this is the part I need to clarify what exactly is in order to buy and replace it. I am attaching a photo.

                          Thanks in advance all!
                          looks like this could be the one, https://cdn.badcaps-static.com/pdfs/...88cf177dc8.pdf
                          they have them on ebay

                          Comment

                          Working...
                          X