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    #1

    Replaced bulging caps, and pop... nothing

    I have one of those va912b's with a bad power supply. I replaced 3 of the caps that were bulging, and when I plugged it pack in, I heard a pop (not an exploding cap) and nothing happened. Did I fry it with a bad joint or something? Or should I just replace the other caps too (except the big one).
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    #2
    Re: Replaced bulging caps, and pop... nothing

    Now with pics of my masterless work. I circled the new caps, and the only joint that rally concerns me is the bottom one with the slight scorching around it (that was there before I got to it). I struggled with that joint.
    Attached Files

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      #3
      Re: Replaced bulging caps, and pop... nothing

      Show us a picture of the switchers and the diodes. Those are the other things that tend to go "pop". Also a complete pic of the underside of the board would help too, as there are a lot of SMD components on that side.

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        #4
        Re: Replaced bulging caps, and pop... nothing

        Originally posted by Karstedt View Post
        I heard a pop (not an exploding cap) and nothing happened.
        Generally, when you see 3 bad caps, you might want to replace them all.

        Did you install one of the caps backwards?
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          #5
          Re: Replaced bulging caps, and pop... nothing

          Originally posted by Trinite View Post
          Show us a picture of the switchers and the diodes. Those are the other things that tend to go "pop". Also a complete pic of the underside of the board would help too, as there are a lot of SMD components on that side.
          Well, I can post some different angles and a complete underside. But I can't really get a much closer pic of anything... they get way out of focus.

          Originally posted by retiredcaps View Post
          Did you install one of the caps backwards?
          Definitely not.
          Attached Files

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            #6
            Re: Replaced bulging caps, and pop... nothing

            Ya, I agree with replacing the others as well. Usually when they are in a cluster like that, they all get affected. You could take off the other ones and test them with a meter if you have one. Also check the bottoms of them for bulging, for some reason some brands tend to go bottom first then bulge at the top if it's that bad.

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              #7
              Re: Replaced bulging caps, and pop... nothing

              I'd expect that area of a power supply to use low ESR caps. I am not familiar with the "NTE" capacitors you used as replacements. What are their specs and how do they compare to the originals? They're not a brand I've heard of before, so I'm unsure of their long term reliability.

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                #8
                Re: Replaced bulging caps, and pop... nothing

                If you have no power and no power LED, then check the bridge rectifier (BD101) for shorts. Number the pins 1-4 and put your multimeter on 200 ohms.

                With power off and lcd unplugged, measure pins 1-2, 1-3, 1-4, 2-3, 2-4, 3-4. Any reading under 30ohms suggests that the bridge rectifier may be shorted.
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                  #9
                  Re: Replaced bulging caps, and pop... nothing

                  Originally posted by yyonline View Post
                  I am not familiar with the "NTE" capacitors you used as replacements. What are their specs and how do they compare to the originals?
                  They are higher voltage with the same uF as the originals. I don't know the other specs, and haven't used them before either. They were available at the local electronics parts store, and they use them for repairing LCD's...

                  Originally posted by retiredcaps View Post
                  If you have no power and no power LED, then check the bridge rectifier (BD101) for shorts. Number the pins 1-4 and put your multimeter on 200 ohms.

                  With power off and lcd unplugged, measure pins 1-2, 1-3, 1-4, 2-3, 2-4, 3-4. Any reading under 30ohms suggests that the bridge rectifier may be shorted.
                  You are correct, no power, no LED. I'll check that this weekend. Thanks.

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                    #10
                    Re: Replaced bulging caps, and pop... nothing

                    Also check this fuse, the live wire goes through this fuse before anything else.
                    Its probably blown, but without finding out the cause, it will probably blow again.

                    mastertheknife.
                    Attached Files
                    Last edited by mastertheknife; 01-28-2011, 11:07 AM.

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                      #11
                      Re: Replaced bulging caps, and pop... nothing

                      That switcher MOSFET looks a bit fishy to me. If you can get a close look at it, check for any pitting, cracks or discoloration. Also check the fuses (anything labeled with an "f" on the PCB) for continuity. An open fuse will indicate that it is more likely a silicon failure than a capacitor failure.

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                        #12
                        Re: Replaced bulging caps, and pop... nothing

                        Having worked with all sorts of electronics over many years...have never heard the term 'switcher' before.Terminology for many subjects can have different names for different things...so define 'switcher' in English please ???

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                          #13
                          Re: Replaced bulging caps, and pop... nothing

                          Originally posted by Rtech View Post
                          Having worked with all sorts of electronics over many years...have never heard the term 'switcher' before.Terminology for many subjects can have different names for different things...so define 'switcher' in English please ???
                          The term "switcher" is short for "switching transistor". Essentially, it is a high power transistor (generally a MOSFET type, but also can be bi-polar) that is used in combination with a PWM (pulse-width modulation) circuit.

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                            #14
                            Re: Replaced bulging caps, and pop... nothing

                            Thanks,I know what Mosfets etc are, as I am electronics qualified,but you are the only one I have ever seen use the term on here,or anywhere else. You learn every day ....eh

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                              #15
                              Re: Replaced bulging caps, and pop... nothing

                              The fuse is definitely blown. But I don't know about what I'm assuming is the switching transistor you're talking about. It's definitely funny looking, but I don't know what it's supposed to look like. I can't read it either, so I don't what to replace it with.
                              Attached Files

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                                #16
                                Re: Replaced bulging caps, and pop... nothing

                                Originally posted by Karstedt View Post
                                The fuse is definitely blown. But I don't know about what I'm assuming is the switching transistor you're talking about. It's definitely funny looking, but I don't know what it's supposed to look like. I can't read it either, so I don't what to replace it with.
                                IIRC, I believe that is a plastic cover. If you remove the screw, it should come off and expose the mosfet underneath.

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                                  #17
                                  Re: Replaced bulging caps, and pop... nothing

                                  looks more like it has blown apart

                                  your only chance would be to find the missing chunk with the part number on it..

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                                    #18
                                    Re: Replaced bulging caps, and pop... nothing

                                    Data Sheet for the part is as follows:-
                                    http://pdf1.alldatasheet.com/datashe...FSDM0565R.html

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                                      #19
                                      Re: Replaced bulging caps, and pop... nothing

                                      https://www.badcaps.net/forum/showth...highlight=acer
                                      looks like this acer uses the same p/s
                                      wonder if samson still has to help identify parts?

                                      Don't miss Rtechs post above
                                      Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!

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                                        #20
                                        Re: Replaced bulging caps, and pop... nothing

                                        Used by some Acers,some Viewsonics and Hanns G HX191.....plus no doubt many others.

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