820-3115-B no chime and no picture after bad Waterdamage

Fizzl92

Member
Hello,
i have problems with an 820-3115-B. The board had bad water damage and no green light. I cut off the bad damaged Thunderbolt area, replaced the SMC and a lot of other stuff. Now it has a green light and turns on again. The remaining problem is that it beeps if i take the ram out (speakers are ok) but wont chime. Also it has no Picture and no Backlight (missing LCD_BKLT_EN ; i already exchanged LP8550 and the LVDS witch were damaged too) Could it be an SMC Issue (bad soldering or maybe bad SMC ; but it has a green light after the SMC exchange)? At this point i´m stuck.
Thanks for any help!
 

dukefawks

Administrator
It is beeping so the CPU is alive. This one is probably going to suck. Make sure you have good RAM and try 1 slot at a time.
 

Fizzl92

Member
Yes, Vcore is there at 1.113V. With no ram installed it beeps 1x every few seconds. I tried with different ram sticks and every Slot on its own. While testing i noticed, that the HDD makes clinking sounds at the beginning and stays spinning after that and that after a minute or two if i leave it running the ODD makes its "sound" (the sound that it normally makes at the beginning of every Startup directly before the chime) but still no chime. Could it be one of the sensor issues, where the cpu is running incredible slow? I set it aside and let it run now for a few hours and look if it chimes later maybe...
 

Fizzl92

Member
I removed U9410 and some caps near it and some more near U3890 as these where burned so badly, that eg. U4910 is missing 11 pads including the groundpad (the chip looked like a ball as i opened the machine the first time). So i thought that there is no hope for TB and that it would be better if no voltage is going in this circuit anymore. I did this after i restored the green light. After i "cut off" T29 the fan starts to spin.
 

dukefawks

Administrator
Well, at this point it can be anything that stops the board from finishing POST. Everything is alive else it would not beep. Corrosion somewhere or under SMC/PCH/CPU. Maybe remove firewire chip if there was crap there. Does not look very good at this point.
 

Fizzl92

Member
Could it still be affected from Thunderbolt? I "cut off" nearly everything from PP15V_T29 but there is still a short on that line. Could it be a bad soldering on the SMC i exchanged? Firewire Chip and area looks pretty clean still but if nothing else helps i´ll remove that chip too.
 

dukefawks

Administrator
As I said this could be anything. Probably a short in the board from T29 rail. Bad SMC solder is possible, anything.
 

Fizzl92

Member
Thank you for the help. If i have the time i´ll practice a bit with this one. Not everything is fixable but it was my first SMC exchange and it worked, so i learned from it...
 
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