I'm working on a 820-01521-A board that had liquid damage and corrosion in the CPU VCCSA circuitry. I replaced a visibly burnt FET driver for
PPVCCSA_S0_CPU (Q7291) and several components around it. This restored PPVCCSA_S0_CPU to the expected 0.8-1.1V.
However, I'm missing CPU VORE (PPVCC_S0_CPU). The big coils all measure over 10Ω to ground, no I don't suspect the CPU to be shorted out.
PPBUS_G3H is 12.6V and ALL_SYS_PWRGD is 1.8V. DFU Restore concludes successfully with a padlock on the host machine (but no video on the target machine).
CPUCORE_FCCM, the enable signal for U7230, is around 2V for a few seconds, then drops to 0V instead of increasing to 5.1V like on a good board.
How can I convince myself that the CPU is damaged and beyond repair?
PPVCCSA_S0_CPU (Q7291) and several components around it. This restored PPVCCSA_S0_CPU to the expected 0.8-1.1V.
However, I'm missing CPU VORE (PPVCC_S0_CPU). The big coils all measure over 10Ω to ground, no I don't suspect the CPU to be shorted out.
PPBUS_G3H is 12.6V and ALL_SYS_PWRGD is 1.8V. DFU Restore concludes successfully with a padlock on the host machine (but no video on the target machine).
CPUCORE_FCCM, the enable signal for U7230, is around 2V for a few seconds, then drops to 0V instead of increasing to 5.1V like on a good board.
How can I convince myself that the CPU is damaged and beyond repair?
