820-3435 not booting

arnonabuurs

New member
Mac Air 11 inch came in not working. Liquid damage many month ago, not too much but some sign of corrosion. No red/green light, after reflow SMC light came back but 0.1v on PPBUS. Replaced U7000 and I get 8.6 and fan spin but then the voltage is dropping slowlyy to about 6.5-7v. Also it doesnt boot I only have fan spin. CPU Vcore is present and the CPU gets hot. I guess this might be related to the SPI ROM data lines? Some corrosion around there so will check all of those. However I am wondering about the voltage drop on PPBUS, there is no short in that line.
 

dukefawks

Administrator
The usual measurements around U7000 done? 17/18 27/28 etc. It is also unlikely if the board stopped and the liquid damage was months ago that there will be multiple dead chips.
 

arnonabuurs

New member
I think it might still have had some liquid under some IC after my ultrasonic cleaning. After a weekend lying on the shelf it decided to start working :)
 
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