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820-3437 - SMC_Adapter_EN 0v

Palhano

Palhano

Member
Board arrived without turning on. I found oxidation in the oxidation on R1663/62/66/26. I replaced them all and it didn't work. Checking the voltages, I noticed problems with the SMC. Replaced it and the mac turned on, worked perfect for two days and stopped.

SMC bypass did not work.

PPBus is 8.6v
SMC_reset - 3.3v
SMC_onoff - 3.3v
PLT_reset - 0v
SMC_PM_G2_EN - 3.3v
SMC_adapter_en - 0v

Will there be a problem with the SMC again?
 
2informaticos

2informaticos

Administrator
Staff member
This signal switches between 1 and 0, depending the power state; check the table from page 59.

Are you using original Magsafe 2 charger?
Do you get amber light?
3V3_SUS is there?
 
Palhano

Palhano

Member
I was on vacation and came back today, the Mac is working. I'll keep testing and hope to stop again, to check the lines.

I had the original MagSafe 2. With amber light.
 
Palhano

Palhano

Member
I don't have the 3V3_S5, it's impossible to have the _SUS!

I didn't find any other components damaged or shorted.

PPVRTC_G3H - 3.3v
PP3V3_S5_SMC_VDDA - 3.3v
PP3V3_S5_AVREF_SMC - 3.3v
 
Palhano

Palhano

Member
U7501
23 - 8.6v
22 - 3.3v
12 - 3.3v
13 - 1.9v (strange)
29 - 5v
21 - 3.3

Diodo mode
L7520 - both pins 0.450
L7560 - both pins 0.360
 
Palhano

Palhano

Member
Because of pin 13, I analyzed the area near U7501.

The R7539 was altered on the board, outside the board measuring 20k. I compared it in diode mode with another board, pin 1 on the R7539 was 0.500 and on the good board it was 0.740. I changed the C7539 and now I have 20k on the R7539. The board turned on, but pin 13 of the U7501 is still 1.9v.

Now it's time to test! If it turned on because of the heat or if that was the problem.
 
Palhano

Palhano

Member
Reading quickly, I got confused with the 3v one.

But it brought me to the issue of the resistor. Could this be the problem? The Mac continues to work.
 
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