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820-3476 - Green light but no fan spin

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vaswaniraj

New member
Hi Team,

Received a Macbook Pro with board 820-3476. The green light turns on and then turns orange, but the fan does not spin. I checked ppbus_g3h and i get 12.58v. Can someone advice me further to trouble shoot this board. Thanks.
 
V

vaswaniraj

New member
Thanks. Checked all power rails however, PP3V3_S3,PP3V3_S0, and PP3V3_S4 aren't present. Any further troubleshooting tips?
 
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vaswaniraj

New member
The resistance to ground on PP3v3_s4 is 8.70 k ohms. I checked R8000 and on Pin 2 - PP3v3_s4 is showing 8.70 k ohms. I am measuring resistance to ground by putting the Red probe to ground and black probe to the test point. Correct me if i am wrong in measuring resistance to ground. Please advice further. Thanks.
 
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vaswaniraj

New member
Checked U6100, U1950, and U1900. Only U1900 has some mild corrosion but, only on unconnected and ground pins. U6100 and U1950 are fine. However, power rails PP5V_S4 and PP3V3_S4 are missing. On further investigation, U8020 was found to be getting hot. Can you please advice for further investigation?
 
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