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820-2879 one beep

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  • 820-2879 one beep

    Heya guys

    I have this board 820-2879 .When I bought it boot up once and die. I mean literals just say good bye and never start up again. Except annoying beep

    I opened it there was some funny paper on the RAM but well it doesn't charge battery from start. So I decide first work on it and change isl625 now I am stuck with this RAM problem. On L7330 is 0.22 V
    I changed already u7300 twice and still same issue. I was thinking to change Q7330 as a start point but that mos look OK. Any advice where to start?

  • #2
    Post first diode mode at L7330, red probe to ground.
    Also post some voltages for U7300; pins 10, 11, 14, 15.

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    • #3
      So L7330 on diode mode 0.270

      pin

      10:3.30
      11:3,28
      14:5
      15:5

      I know I said Q7330 look ok but pin 3-4 should not have 0.002 on diode mode, right? Its a stupid question but I rather ask and be stupid a minute that stay stupid
      Last edited by OndrejT; 04-16-2019, 05:34 AM.

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      • #4
        "pin 3-4 should not have 0.002 on diode mode, right?"
        Not really true.
        If U7300 detects a problem, it will short G-S of Q7330, to avoid any output voltage.
        You can remove Q7330 and see if is short indeed.

        Check all components and traces around U7300.
        Change it, if nothing strange found.

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