820-3115 Green light, no fan spin

[kevinklinkmuller]

Liquid damaged by the LVDS connecter. Can't see anything anywhere else. Already replaced u7000 and q7085

on U7000
Pin1 = 0v
pin2 = 17.5v
pin3 = 4.2v
pin9 = 0v
pin12 = 3.47v
pin14= 3v
pin 15 = 0.3v
pin17 = 12.54v
pin19 = 5v
pin20= 5v
pin27 = 17.5

 

[2informaticos]

PPBUS_G3H looks good, no need to work on U7000 area.
Do you get 3V3_S5/SUS?

 

[kevinklinkmuller]

3v3_S5 is pulsing like crazy. 0 - 3.3V

3v3_SUS is pulsing as well but from 0 - 1v and then 0 - 0.04v

 

[kevinklinkmuller]

PP5V_S5 is pulsing on u7200. but PPBUS_S5_HS_OTHER_ISNS is stable of course

 

[kevinklinkmuller]

Am I correct in thinking. If a 5V line has issues and a 3V line has issues, there's no point looking at the 3V line since it's produced by the 5V anyway and the issue is most likely with the 5V?

 

[2informaticos]

Do you get pulse at the other big coils?

SMC may detect a short/overcurrent and cycles the power.
Check if something changes in SMC bypass mode.

 

[kevinklinkmuller]

actually I just realised PPBUS also pulses but not strong. Every few seconds it'll go down to 12.3 and then back to 12.56

so L7030 is actually pulsing and so is L3895

 

[2informaticos]

"Check if something changes in SMC bypass mode."
???

 

[kevinklinkmuller]

Sorry, nothing on SMC bypass

 

[2informaticos]

SMC_PM_G2_EN is pulsing; confirm that.

Make short over R7271 and check if L7220 gets stable voltage.
If not, make short over R7272 and check if SMC_PM_G2_EN fluctuates.

 

[kevinklinkmuller]

SMC_PM_G2_EN is pulsing yep

made short over R7271 and L7220 is now stable.
Board is drawing more power now, but no fan spin yet

 

[2informaticos]

So your problem appears when 5V tries to come on.
Check diode mode to ground on all big coils.
Also check any other output power rail, and after Power FETs also.

 

[kevinklinkmuller]

Well crap. Most of the big coils are 0.000V to ground. All the CPU coils it seems. So PCH is toast?

 

[2informaticos]

CPU coils show very low value as normal; aprox 1 ohm for i7.

PCH coils and RAM have good value?
Check them for voltage pulse also.

 

[kevinklinkmuller]

Ok just checked, CPU coils are around 1.5 ohms so should be ok

The one coil that stands out is 7260 which is a straight short to ground. Shall I inject and see what's up?

RAM coil numbers look good. Which one is PCH?

 

[kevinklinkmuller]

I injected the line, found C6213 short. Removed. Short gone. Removed bridge on R7271 and MacBook now turns on WOOOO. thank you 2informaticos

 

[2informaticos]

Glad to hear is solved now.