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Toshiba C660 voltage rail problem

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    #1

    Toshiba C660 voltage rail problem

    Hi all,
    I have this problem, i am missing a 1.5V rail. It is a LA-6842P rev.1.0 board (page 39 of the attached schematic).
    The MOSFET-s are OK, VTTP_EN is 5V, i have 5V at Low Driver Gate, but nothing on the DH (pin 13).

    Could it be the chip?
    Is there a posibility that anything else in the circuit could be wrong?

    Regards,
    Darko
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    #2
    Re: Toshiba C660 voltage rail problem

    What do you get at pin6 PGOOD pin?

    Comment

      #3
      Re: Toshiba C660 voltage rail problem

      It was the chip, i replaced the stock G5603RU1U with TPS51117 and it works. Now when i have the 1.5V and all power supplys to clock generator, i don't have frequency on the crystal. :|
      Suspect the clock generator now.

      Comment

        #4
        Re: Toshiba C660 voltage rail problem

        Originally posted by whaldsz View Post
        What do you get at pin6 PGOOD pin?
        Nothing, logical low voltage.

        Comment

          #5
          Re: Toshiba C660 voltage rail problem

          Originally posted by lord View Post
          Nothing, logical low voltage.
          And you get a voltage at PL802? If so, then there's something wrong with this circuit. PGOOD pin should be high. Is the +5VS and PR811 ok?

          Comment

            #6
            Re: Toshiba C660 voltage rail problem

            what is the symptoms of this fail? (LED, fan, display)
            ...the quieter you become the more you are able to hear...

            Comment

              #7
              Re: Toshiba C660 voltage rail problem

              I don't exactly understand what you mean, could you clarify more about the issue you are having.

              Comment

                #8
                Re: Toshiba C660 voltage rail problem

                Originally posted by lord View Post
                Nothing, logical low voltage.
                Recheck voltages.
                Could be new replaced chip is damaged.

                Comment

                  #9
                  Re: Toshiba C660 voltage rail problem

                  I repaired the 1.5V rail with replaceing the IC controller, now i miss +CPU_CORE from PU13, which i replaced already.
                  Here are the readings from PU13:
                  PGOOD at pin 1 is low
                  CLK_EN# at pin 40 is 3.3V
                  VR_ON at pin 38 is 3.3V (What does this pin do?)

                  I also noticed that i don't have any frequency readings from clock generator on Y1. All input voltages to clock generator and CK_PWRGD/PD# is low (i think this is supposed to be low because Q37 connects this pin with ground after CLK_ENABLE# goes hi).
                  I tried to replace the crystal, and i have one more used RTM890, so i tried with that but lo luck. I also tried with this used RTM890 but also no luck.

                  Does anyboy knows which one has to work first: the +COU_CORE rail or the clock generator?

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