got a macbook pro A1398 (820-3332-A) with an orange light on charger even battery is not connected. board is clean with no signs of liquid damage. upon checking for any short circuit via multimeter, at L7550/L7560 gives only 1ohms, and at L7510/L7520/L7530 gives only 0.9ohm. and if i set to Diode mode or continuity test at those points it gives a ZERO reading. most likely a damaged U1000?
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Last edited by salawayon; 05-30-2022, 06:28 AM. -
Re: Troubleshooting dead Apple MacBook Pro A1398 (820-00426-A)
Not enough info to draw that conclusion, but it is low. Usually if you have a shorted CPU, then one of the high side MOSFET's is shorted and PPBUS_G3H is also shorted to ground as a result. Often this is from an issue with the PWM driver IC (in this case U7400). This can be from liquid damage, or even the decomposing corpse of a dead bug next to that IC.
Do 1V voltage injection with thermal camera. You might be lucky and it's a shorted cap or low side MOSFET. -
Re: Troubleshooting dead Apple MacBook Pro A1398 (820-00426-A)
When it is warm, Ivy Bridge can measure close to 1 ohm.OpenBoardView — https://github.com/OpenBoardView/OpenBoardViewComment
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