Problem in 5V Fan

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  • Agent24
    I see dead caps
    • Oct 2007
    • 4950
    • New Zealand

    #21
    Re: Problem in 5V Fan

    Originally posted by Th3_uN1Qu3
    Impossible, as this particular fan controller chip is a "dumb" model, it's just a linear regulator. RPM is not even monitored in most laptops for other than displaying it to some diagnostic software... The fan speed is based on the thermal sensors monitored by the EC which is U20 in this case.
    Sorry, that's what I meant. If the EC\U20 was getting bad sensor input it may not be sending the right signal to U41.
    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
    -David VanHorn

    Comment

    • magneh
      Badcaps Veteran
      • Apr 2014
      • 588
      • Portugal

      #22
      Re: Problem in 5V Fan

      Originally posted by Th3_uN1Qu3
      I can answer that. Check R308. See if you get different voltages at each end of R308. If you aren't getting anything on either side, follow the trace from R308 to pin 76 of U20 IT8512E.

      If there's nothing on pin 76 either, then U20 is faulty and must be replaced. But i wouldn't bother with that for a fan... You can easily make a little replacement circuit to enable the fan to still be thermally controlled.
      Hello!

      UPDATE :

      Mesured voltages on both sides of R308 and I get 0.01V .
      On pin76 of IT8512E and I get 0.01V.

      Seems that U20 is the faulty component right?
      Gonna try to find a new one .

      I've also noticed some capacitors that seem weird. Could you guys tell me if they seem blown?

      Thanks for your help!
      Attached Files

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30978
        • Albion

        #23
        Re: Problem in 5V Fan

        c346 is toast.
        i think the other one just got hit by some soot.

        question now is, did it die - or was it killed?

        and 2 of the pins on the chip look like they may have been hit by a blast - is the chip package split open?
        Last edited by stj; 05-05-2014, 05:14 PM.

        Comment

        • Agent24
          I see dead caps
          • Oct 2007
          • 4950
          • New Zealand

          #24
          Re: Problem in 5V Fan

          C342 looks like it's just got a bit of dirt or something next to it, but that C346 looks like it might be burnt out if it's not just more dirt.

          According to the schematic (Page 71) that C346 looks like it's just part of supply filter for the analog supply to U15, which seems to provide the RAM clock signals and doesn't look like it has anything to do with the fan, though.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

          Comment

          • magneh
            Badcaps Veteran
            • Apr 2014
            • 588
            • Portugal

            #25
            Re: Problem in 5V Fan

            Hello!

            I think the board came with these components in these condition.
            She is booting ok, testing OK but cant keep CMOS settings and the fan doesnt spin.

            I've found a similar board to this one, one that is dead.
            Maybe I can take those capacitors and U20 from the dead one, and swap them.

            What do you guys think?

            Thanks!
            Last edited by magneh; 05-05-2014, 05:41 PM.

            Comment

            • Agent24
              I see dead caps
              • Oct 2007
              • 4950
              • New Zealand

              #26
              Re: Problem in 5V Fan

              Sounds like a plan. Not sure I would bother with the capacitors though, just buy some fresh ones. Trying to solder SMD capacitors etc that already have solder on the terminals is a PITA in my opinion. Plus if you are desoldering and stuffing around with them they could get heat damaged - and you can't be sure the ones you removed are not bad already or even the right value.
              "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
              -David VanHorn

              Comment

              • magneh
                Badcaps Veteran
                • Apr 2014
                • 588
                • Portugal

                #27
                Re: Problem in 5V Fan

                Originally posted by Agent24
                Sounds like a plan. Not sure I would bother with the capacitors though, just buy some fresh ones. Trying to solder SMD capacitors etc that already have solder on the terminals is a PITA in my opinion. Plus if you are desoldering and stuffing around with them they could get heat damaged - and you can't be sure the ones you removed are not bad already or even the right value.
                You're saying I should buy regular caps and change them?
                Not SMD?

                Or I should just change U20 and see from there?

                Thanks!

                Comment

                • Agent24
                  I see dead caps
                  • Oct 2007
                  • 4950
                  • New Zealand

                  #28
                  Re: Problem in 5V Fan

                  No, if you buy new ones you should buy SMD ones the same.

                  I just mean re-using SMD ones from an old board is probably a bad idea: no markings, difficult to test, and easy to damage while desoldering.
                  "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                  -David VanHorn

                  Comment

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