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820-2850 No power. Green light only

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  • 820-2850 No power. Green light only

    hey guys. Been a while since posting. Must of learnt something!
    Am now stuck on a old 820-2580 board. Seconds away from giving up and this post is my last resort.

    PPBUS_G3H is not holding and is always changing values. From around 8v to 12.6v.
    F7040 is fine and I even changed U7000 off a working board. Same result.
    R7020 and R7050 are those sense resistors. I don't quite understand how they work although the readings seem fine. Can't find any shorts.
    Possible for some nudges in the right direction??
    Thaks again.



  • #2
    Measure resistance between pin 17/18 and between pin 27/28 from U7000

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    • #3
      can close this. I fkd the board good and proper. Made a fire

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      • #4
        So here's an update.. ended up repalacing the board that caught fire. Bought a supposedly working board from eBay, Rnrcomputers to be precise. Long story short. This board doesn't work either. Has no green orange light.

        Took 3 weeks to arrive and really don't have time to send it back and wait so I thought I'd diagnose. Found CHGR_CSI_R_N between r7020 and r7022 missing. Jumped it. Got a green light and laptop powers up and all works bar an x for the battery.

        So the smc is not seeing the battery I'm guessing.. And pins 4 and 6 on the battery connector are the lines that tell the smc there is a battery?? Am I on the track?

        u4900 creates smbus_smc_bsa_scl and goes to battery then to u7000

        i cant find any other tracks not present. Is this a dead u7000? Proper brain stuck now.

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        • #5
          So this is obviously a liquid damaged board you got. In most cases no battery recognized is a dead SMC and U7000. Did you test with a good battery? Yours could have died in the fire with the other board. Also the battery indicator can cause issues, disconnect it to be sure.

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          • #6
            Thanks Duke, I think your right, it does seem so.. I'm going with dead, I tested with two working original batteries. Only had a fan, dc port and battery connected too.
            Probably best off doing an eBay return at this point. It cost me $675AU!

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            • #7
              actually probably try changing u7000 first I reckon

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              • #8
                675? Fuck that shit. Return that garbage.

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                • #9
                  Changed it, no difference. Got ripped. Sending it back.

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                  • #10
                    One last go...
                    r5281 is 3.4v r5280 is .5v
                    i don't have a working oscilloscope to know if pins 2 of r5280 and r5281 are doing what they are supposed to do right now either.

                    Changed u7000 r5281 and r5280. Something is fucking up the data lines.

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                    • #11
                      SMC is dead...

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