已解决： 820-3208-A Board no green light - MacBook Air 11" Mid 2012

820-3208-A Board no green light

Hello Guys,

I have a problem that I would like some help with on this 820-3208-A logic board I’m working on. The board looks really clean and there was no water damage,. However, there was some corrosion around U6990 chip and there is no green light on the magsafe. After cleaning the corrosion and replacing the U6990 chip I only get 2.74 V on pins 2 and 4. Pins 6 and 8 both have 15.50V going in. I checked for a short to ground on the pp3v42_g3h and did find a small drop to ground. I then felt around and noticed the SMC is really hot to touch. Please tell me that the SMC is not bad!!!!!

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发帖于: 2020年6月18日

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Have you checked for corrosion under SMC? That seems like the most probable cause.

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Ben is right. Remove the SMC and see if PP3V42_G3H comes back.

由 Chris Stables 完成的 2020年6月19日

Thanks Ben, I will check but I'm fairly certain that the smc area is very clean. Just don't understand why I would be getting any voltage at all if there is a short on that line on the smc? I get 2.7V! Dont want to mess with smc if I can avoid it!!!

由 Roger 完成的 2020年6月19日

Hey guys is it possible that u5010 (SMC reset-L) is shorted and causing the smc chip to heat up? Still baffling!

由 Roger 完成的 2020年6月20日

@Roger What do you get on PPBUS_G3H?

由 Chris Stables 完成的 2020年6月20日

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2012年中 MacBook Air 11"

820-3208-A Board no green light

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