Tony Tone
Member
I have this MB that came in stone dead several weeks ago. There is no water damage. When I checked the rails I found there was no S4 rail. So what do I do when I see there is no S4 rail? Change the SMC.
I changed the SMC and all was good. Customer comes back in a few days crying there is no audio (I never checked audio). Indeed no audio. I have inventory of all new parts and some used parts. So yes, I tried several KNOWN good DCIN boards from inventory and from other peoples working machines. I've tried KNOWN good flexs, speakers and checked everything I could find related to audio. It is now week 3 I've been working on this board 40+ hours already. Reaching out on some of the FB forums I found someone smart enough to suggest to try another SMC. Bingo, it worked. I did get sound back. But then I had other issues like backlight, no keyboard, no trackpad, dying after boot. I've put in 12 different SMCs 20 times and I can't find the right SMC that working with audio before (my SMC area has been worked so many times traces are beginning to show so I've had to use solder mask on those parts). I'm just getting the same results no matter what I do. What I am coming to find is that on pin 2 I get 3.4, so I guess this is high coming from SMC. My question is why is it high? How do I make it low? So all my voltages are going to ground on pins 4&5. So I thought I would experiment by lifting pin 2 to see what happens. And I do get my voltages on 4&5 but no sound. I have no shorts or broken traces. I've tested just about all caps and resistors on all these lines and kinda stuck. NO AUDIO whats ever.
I changed the SMC and all was good. Customer comes back in a few days crying there is no audio (I never checked audio). Indeed no audio. I have inventory of all new parts and some used parts. So yes, I tried several KNOWN good DCIN boards from inventory and from other peoples working machines. I've tried KNOWN good flexs, speakers and checked everything I could find related to audio. It is now week 3 I've been working on this board 40+ hours already. Reaching out on some of the FB forums I found someone smart enough to suggest to try another SMC. Bingo, it worked. I did get sound back. But then I had other issues like backlight, no keyboard, no trackpad, dying after boot. I've put in 12 different SMCs 20 times and I can't find the right SMC that working with audio before (my SMC area has been worked so many times traces are beginning to show so I've had to use solder mask on those parts). I'm just getting the same results no matter what I do. What I am coming to find is that on pin 2 I get 3.4, so I guess this is high coming from SMC. My question is why is it high? How do I make it low? So all my voltages are going to ground on pins 4&5. So I thought I would experiment by lifting pin 2 to see what happens. And I do get my voltages on 4&5 but no sound. I have no shorts or broken traces. I've tested just about all caps and resistors on all these lines and kinda stuck. NO AUDIO whats ever.
