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820-3115 smc troubleshoot

J

jadao

Member
This one was water damage, no magsafe light, with two shorts : first on PP3V42_G3H (U7941) and second one was an internal short on PPVIN_S5_HS_OTHER_ISNS.

Fixed these issues and we are back with green light but ppbus_g3h was 8.22V :(

Before messing with smc, I checked smc_reset_l and it was present at 3.4V.
I checked pp5v_s5_ldo and it was pulsing because 5V3V3_REG_EN was pulsing and SMC_PM_G2_EN was pulsing...

For ultimate testing I decided to cut the power (PPVIN_S5_5VS3 8.22v) to U7200 and at my big surprise SMC_PM_G2_EN 5V3V3_REG_EN were steady at 3.4V but PPBUS_G3H is still 8.22V.

So my partial conclusion is that U7200 will need to be replaced.
My question in the meantime is : does PP5V_S5_LDO missing causes also SMC to not fully turn on? I am still suspecting an smc issue...
thanks
 
2informaticos

2informaticos

Administrator
Staff member
"was an internal short on PPVIN_S5_HS_OTHER_ISNS"
What exactly did you find there?

"I decided to cut the power (PPVIN_S5_5VS3 8.22v)"
Did you get 5V_S5 then?

Remove F7040 and test L7030 voltage.
If you get 12.5V, your problem is on the system side of PPBUS_G3H.
 
J

jadao

Member
Hello 2informaticos, for the internal short, there was a burning hole right next to R5410, ppbus_g3h was dead short to gnd. I gently scraped the burned hole and isloted the shorted track. This bring back normal diode mode 0,440 on ppbus_g3h. I had to reroute 2 wires to U5410 and of course to connect back with ppbus_g3h.

No I didn?t get 5V_S5 because U7200 wasn?t anymore powered on it?s VIN pin 16. But this test let me find out that SMC_PM_G2_EN was back steady and stable, this let me think that u7200 when powered up is causing SMC_PM_G2_EN to pulse continually.

Yes easy and good idea, I removed F7040 and tested L7030 voltage but it still 12,28V.
 
2informaticos

2informaticos

Administrator
Staff member
"L7030 voltage but it still 12,28V"
Didn't have 8.22V with F7040 in place???

12.28V usually means no communication between U7000 and SMC.
Check diode mode (red probe to ground) and voltage for SCL/SDA lines of battery bus.
Keep F7040 removed, untill get correct voltage at L7030.
 
J

jadao

Member
Oh so sorry! with fuse in place it was 12.22V with F7049 removed it was same thing 12.28V I am confused with macbook air:) there seem no short on ppbus_g3h with 0.424 on diode mode. Sorry about that.

I just replaced U7200 and the board turns on an chimes! One variable less! U7200 was messing all pp5v_s5 down up to Smc_pm_g2_en.

I still measure 12.25v on ppbus_g3h, it works fine with a baterie but not charging and no orange light.
Diode mode on SDA line shows ... a full short to ground... SCL is ok at 0,499.

Finger crossed will start first with u7000, damn this board had a lot of bad chip + the burning hole most likely chinese charger not triping with water...
 
J

jadao

Member
I am lucky on this one it was U7000 ISL fully shorted on sda pin!
Diode mode on SDA is back to normal and exactly same as SCL line.
I just have to put backa new ISL6259, test the board, sensors etc.
You can consider it solved! Thanks 2informaticos?
 
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