How to unsolder transistor

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  • Rockguy
    Senior Member
    • Jan 2015
    • 71
    • USA

    #21
    Re: How to unsolder transistor

    I should have known that since I put one lead of my meter on the tab when testing it Duh

    Comment

    • Rockguy
      Senior Member
      • Jan 2015
      • 71
      • USA

      #22
      Re: How to unsolder transistor

      Originally posted by mmartell
      I think you'll be fine. Trace those connections then verify with your meter they are still good then flow some solder on the large pad and see what you've got.
      Where the solder remains, I have continuity with the other transistor tabs. Obviously where the copper is torn out, there is nothing. There is no damage where the legs were.

      Is the goal to try and flow new solder attaching to the old and filling the damaged area? Do I need to get a copper sheet and epoxy it in there?

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30932
        • Albion

        #23
        Re: How to unsolder transistor

        if the tabs are all connected, you could solder a stiff copper wire across a few.
        your really just trying to physically hold it down.

        Comment

        • mmartell
          Badcaps Legend
          • Oct 2013
          • 3189
          • Canada

          #24
          Re: How to unsolder transistor

          Did you test the fet for short after you pulled it ? How did you know this one was short and not another one that is in parallel ?

          Comment

          • Rockguy
            Senior Member
            • Jan 2015
            • 71
            • USA

            #25
            Re: How to unsolder transistor

            Originally posted by mmartell
            Did you test the fet for short after you pulled it ? How did you know this one was short and not another one that is in parallel ?
            Yes, I tested it out of circuit. With that FET missing, I briefly fired up the tv and it was working so I should be good when I put this new one in. I'm planning on messing with that today if nothing comes up. I was working too much the last couple of days.

            Comment

            • Rockguy
              Senior Member
              • Jan 2015
              • 71
              • USA

              #26
              Re: How to unsolder transistor

              Originally posted by stj
              if the tabs are all connected, you could solder a stiff copper wire across a few.
              your really just trying to physically hold it down.
              That does seem like another option. Thank you for suggesting it. If flowing solder in there doesn't work as well, I can do that.

              Comment

              • Rockguy
                Senior Member
                • Jan 2015
                • 71
                • USA

                #27
                Re: How to unsolder transistor

                Originally posted by Rockguy
                That does seem like another option. Thank you for suggesting it. If flowing solder in there doesn't work as well, I can do that.
                As I feared, the solder will not stick to the area where the solder and everything was torn out. I'm gonna have to go with another plan.

                Comment

                • SteveNielsen
                  Retired Tech
                  • Jun 2012
                  • 2327
                  • USA

                  #28
                  Re: How to unsolder transistor

                  Can't you get solder to take where the copper is still intact? It may be enough to do the job. As I said earlier my concern is heat sinking the transistor enough through it. I wouldn't glue copper onto the area unless using highly conductive glue (both electric and heat conductive), but you could try soldering a copper shim to it and then solder the transistor tab to the copper shim.

                  Comment

                  • Rockguy
                    Senior Member
                    • Jan 2015
                    • 71
                    • USA

                    #29
                    Re: How to unsolder transistor

                    Originally posted by SteveNielsen
                    Can't you get solder to take where the copper is still intact? It may be enough to do the job. As I said earlier my concern is heat sinking the transistor enough through it. I wouldn't glue copper onto the area unless using highly conductive glue (both electric and heat conductive), but you could try soldering a copper shim to it and then solder the transistor tab to the copper shim.
                    Yes, I can get solder to take where the old stuff is still there. Understood on the copper. I won't glue that in there. Your idea of soldering a copper shim sounds plausible. I got a tip from tom66 to possibly buy a tiny heatsink and attach to the top of the FET.

                    Comment

                    • stj
                      Great Sage 齊天大聖
                      • Dec 2009
                      • 30932
                      • Albion

                      #30
                      Re: How to unsolder transistor

                      thick copper wire soldered across 3 tabs (the new one in the center) should conduct the heat better thansticking a heatsink to the resin body.

                      Comment

                      • Rockguy
                        Senior Member
                        • Jan 2015
                        • 71
                        • USA

                        #31
                        Re: How to unsolder transistor

                        Originally posted by stj
                        thick copper wire soldered across 3 tabs (the new one in the center) should conduct the heat better thansticking a heatsink to the resin body.
                        That would be pretty easy too I think. What kind of wire would you suggest?

                        Comment

                        • stj
                          Great Sage 齊天大聖
                          • Dec 2009
                          • 30932
                          • Albion

                          #32
                          Re: How to unsolder transistor

                          the thickest solid copper you can find.
                          got a bit of the stuff used to wire in cookers?

                          Comment

                          • Rockguy
                            Senior Member
                            • Jan 2015
                            • 71
                            • USA

                            #33
                            Re: How to unsolder transistor

                            Originally posted by stj
                            the thickest solid copper you can find.
                            got a bit of the stuff used to wire in cookers?
                            Hmm no. I've got some house wire.

                            Comment

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