820-3115 CPU core appear for 1 seg

MDY

New member
820-3115
I found burnt transistor or mosfet (3 pin chip) on dc jack on 820-2565 dc jack board.

I tested main board with another dc jack but same story. CPU core appear only for 1 seg at 1.12V
I compared all coils with another board 820-2879 and only found differen value at L7260. In faulty board I have 0.173 in diode mode. Red in ground
In working board I have 0.400 in diode mode. Anything more I can measure?
 

MDY

New member
I checked the board and it is not liquid damage. I reflowed with flux rom and clock chip but no change.
 

MDY

New member
Board for i5 and i7 have same bios, right? I mean 3115 is only what I have to look in donor board, right?
 

MDY

New member
Also without bios this board will loooping right? Now it is not looping. CPU core appear for a seg and fan speed for a seg. Nothing more.
 

dukefawks

Administrator
All 3115 BIOSes are the same and should work for testing. Watch out the China parts boards may have the BIOS chip erased!
 

MDY

New member
It is not china board. Comes from a macbook I didnot repair weeks ago with another problem. I was told 3115 board has PCH ussual problems, but I never tried to replace that. What do you think?
 

dukefawks

Administrator
This could be anything if it is not liquid damage. The usual suspects when it was liquid damage is the clock chip or crap under SMC. I very much doubt this board "just" stopped working.
Put back the original BIOS to avoid ME region problems and replace the clock chip.
 

MDY

New member
I checked again the board and found bad looking C4921. I replaced with solder (no heat arround) and now works and power. Make sense C4921 to stop the board from power?
 
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