820-00165: Fan spins, CPU warm, but won't chime or boot.

cobragfox

New member
Hello gents;

Anyone have a suggestion on this issue i'm facing, the logic board powers up, fan does the initial spin, stops then comes back on and stays spinning. Original issue was no power, found U7701 had solder bridge from previous repair causing the short, pulled U7701 and found pins 5 was missing and the previous repair was in an attempt to bridge the connection, but they used too much solder. Replace U7701 and corrected the bridge they were attempting, see pic. I also confirmed pin 5 wasn't bridging 10, 9, 4 and was making connection to C7797.



Board booted up find after but the display wouldn't come on. After shutting it down, this is when the new issue began.

I've replace bios chip, U1900 even though previous had clock signal coming out, confirm U1950 was sending PM_PCH_SYS_PWROK (3.4V).

Any suggestions?
 

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2informaticos

Administrator
Staff member
Any USB activity?
See if USB mouse get light, or better try a boot pendrive with LED; should see it flashing.
If yes, try PRAM reset...
 

2informaticos

Administrator
Staff member
Missing image/backlight + no USB activity point to non-working board...
Which sign made you think reset was done?
 

cobragfox

New member
MagSafe light responds to reset. Regarding pram, meant to say it was attempted with not effect (nothing happened).
 
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