tlough75
Member
Hello, I have yet another 820-3115 but this one is solved. The original complaint was no power and no light on Magsafe. Board was pulled out and power rails were measured. PP3V42_G3H was 3.5v which is normal condition. PPBUS_G3H was 12.26V which is abnormal and an indicator that the SMC not working. The SMC_RESET_L signal was checked via U5010. The reading was .735V which is abnormal and means the SMC is stuck in ?Reset? mode. Logic would dictate that since SMC_RESET_L is created by U5010 that it would be a likely suspect. However, this was not the case. The edge bonding around the SMC was removed to check the solder balls under it and I noticed slight discoloration of a few of the solder balls underneath, so I decide to reflow the SMC with flux.
After letting the board cool, I plugged in the charger and turned on the power supply. There was immediately a green/amber light on the Magsafe and fan spin. PPBUS_G3H was checked and confirmed to be 12.56V which is normal. The board was put back into the chassis and everything was plugged in and the computer was again powered up and confirmed to be working. But now I am left with the question; How does the board now turn on even though the SMC_RESET_L signal was saying the SMC was stuck in reset yet when I reflowed the SMC it now works?
After letting the board cool, I plugged in the charger and turned on the power supply. There was immediately a green/amber light on the Magsafe and fan spin. PPBUS_G3H was checked and confirmed to be 12.56V which is normal. The board was put back into the chassis and everything was plugged in and the computer was again powered up and confirmed to be working. But now I am left with the question; How does the board now turn on even though the SMC_RESET_L signal was saying the SMC was stuck in reset yet when I reflowed the SMC it now works?
