De-Soldering & Soldering Dr-Mos on a Graphica Card

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  • dreico33
    Member
    • May 2018
    • 36
    • Bolivia
    #1

    De-Soldering & Soldering Dr-Mos on a Graphica Card

    Hellow guys, i recently have a Asus 4070 Ti, and a EVGA 3090 Ftw3 both with Dr-Mos Problems.

    My question is this : I am having real difficult time desolderig and solder again a new Dr-Mos. Is taking for ever to do the job, especially when you have to disolder the dr-mos and with the IC you are taking along caps, resistances and ... welcome to hell!

    I am using a pre-heater board with a temp of 120C and a Quick 861DW 480 Temp air 80. And with all these its like a nightmare take out these IC's and apply fresh solder and install a new one.

    So i am asking you if you have seen a guide , how to , or something on how to do the job with minimun risk of making worst.

    Thank you for your time.
    Tags: None
    • ktmmotocross
      Boardkiller
      • Feb 2014
      • 3593
      • slovakia
      #2
      Originally posted by dreico33
      Hellow guys, i recently have a Asus 4070 Ti, and a EVGA 3090 Ftw3 both with Dr-Mos Problems.

      My question is this : I am having real difficult time desolderig and solder again a new Dr-Mos. Is taking for ever to do the job, especially when you have to disolder the dr-mos and with the IC you are taking along caps, resistances and ... welcome to hell!

      I am using a pre-heater board with a temp of 120C and a Quick 861DW 480 Temp air 80. And with all these its like a nightmare take out these IC's and apply fresh solder and install a new one.

      So i am asking you if you have seen a guide , how to , or something on how to do the job with minimun risk of making worst.

      Thank you for your time.
      thats because the temp on preheater is temp on heater element, not the temp on card. use Kprobe to check. i must turn my preheater to maximum temp/400c/ just to have 120c on card by 10minutes. i use 340c on hotair and it desolder drmos by ten seconds
      Last edited by ktmmotocross; 05-14-2024, 05:18 PM.

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        • DynaxSC
          Badcaps Veteran
          • Apr 2021
          • 461
          • Poland
          #3
          I do confirm, 120 C at preheater is much too less, I go 300 C at preheater (2-3 cm distance), and 400-440 at hot air, with a small size nozzle. For desoldering you need more heat as the tin used factory side is leadless (melting at 254 C), where the tin u use for refitting is most probably leaded (melting at 224 C). The smd devices near the mosfets can be blown off position, so use ca 1/3 - 1/2 max. air flow. You need some time to get the right temperature, as the coils near the mosfets are quite massive, and steel the heat from the board, as long as they do not reach temperature.

          Remember to very good isolate the electrolytic caps near the mosfets, they are quite sensitive to heat. They can even explode and hurt your eyes or so, so this is very important. Protective glasses are not a bad idea. For isolation I use some 1 or 2 layer of tetra-pack material and 3-5 add. layers of capton tape, capton towards the heat. Tetra-pack is costless, and reduces the cost as you do not need so much capton tape.
          Last edited by DynaxSC; 05-15-2024, 02:24 AM.

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            • Aliencomputres
              Badcaps Veteran
              • Aug 2019
              • 208
              • România
              #4
              put a picture !

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