Macbook pro 2012 820-3115-B Greenlight no Power on

[platinumsteel]

Gooday people i have a 820-3115-B Macbook pro 2012 that gives me greenlight but does not power on...History of the machine was there was no green-light and dead.And i replaced the ISL chip for brand new 1...Greenlight now but will not power on automatically or fan spin.I checked most of my relevant power rails and i realize that PP5v_S3 is missing...It's drawing 0.02 Amps Possible you guys can help me pinpoint the issue? btw 12.58v on PPBUS_G3H

[dellxps15]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

check bios pins if are ok, check if 3.3 and 5 volt ic is ok.

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

My friend I am getting 0v on all bios pins....What does this mean?

[dellxps15]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

check the 3.3 5v ic u7500 pins

[piernov]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Go through the list of power rails as always…

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Go through the list of power rails as always…

Okay hi here is the list of power rails.I may have added some irrelevant rails but thanks..if any of them are missing kindly let me know and i will add it asap.


PPBUS_G3H = 12.58v

PPBUS_S5_HS_COMPUTING_ISNS = 12.58v

PPBUS_S5_HS_OTHER_ISNS = 12.58v

PPDCIN_G3H = 18.52v

PP3V42_G3H = 3.42v

PPVRTC_G3H = 3.42v


PP3V3_S5 = 0v

PP3V3_SUS = 0v

PP3V3_S4 = 0v

PP3V3_S3 = 0v

PP3V3_S0 = 0v


PP5V_S5 = 5v

PP5V_SUS = 5v

PP5V_S3 = 0v

PP5V_S0 = 0v

[dellxps15]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

PP3V3_S5 = 0v
check why this is 0v

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

okay thanks will go tru and see what happens

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

PP3V3_S5 = 0v
check why this is 0v

Hi again guys am not sure if am at least on the trail but I read on this forum where piernov stated that ''There are power rails derived from PP3V3_S5 and PP5V_S4RS3'' so i checked on PP5V_S4 and it looks like there is a dead short there..I tested that rail on another identical donor board and it's not shorted..So Can anyone of you guide me further on how i should proceed? ..thanks

[SMDFlea]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Use openboardview instead of BoardViewer, it`ll give you a better visual understanding of whats connected to what. http://openboardview.org/

[Flippers McCoy]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

I believe PP3V3_S5 is your immediate problem, I would recommend checking that out before any S4 or lower rails.
Is it shorted to ground?

My computer with my schematics is not available right now so I can't tell you which pins on which components to check out, but I'd check to see if PP3V3_S5 is shorted to ground. If it's not shorted to ground, find the IC that creates it and see why it's not doing its job

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Thanks for the reply..But PP3V3_S5 doesn't seem shorted to ground..And well am a little bit of a newbie and having a hard time finding the IC that creates it in the schematic.Will be grateful for some help.

[KNIGHTWOLF]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Thanks for the reply..But PP3V3_S5 doesn't seem shorted to ground..And well am a little bit of a newbie and having a hard time finding the IC that creates it in the schematic.Will be grateful for some help.

U7200 CREATES PP3V3_S5.Check the ic location on broadview.Inspect for corrosion,bad cap and feedback resistors.

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Thanks a lot knightwolf for pointing it out...I took some voltages measurements and haven't really picked up any corrosion or short... and hoping you all could tell me if i might need to change U7200 still

Vin = 12.58V
VREF= 2.6V
ENTRIP1 = 0V
ENTRIP2 = 0V
VREG5 = 0.8V
VREG3 = 0V
EN0 = 3.7V
PGOOD = 0V

[dellxps15]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

post voltage on L4901 .

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

L4901 is 3.42v on Pin 1 and 2

[dellxps15]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

check resistance on l7220 and l7260

check all u7941 volts
check all u7200 pin voltage.

[piernov]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

There's an issue with your measurements, in post #6 you said " PP5V_S5 = 5v", in post #14 you said " VREG5 = 0.8V". They're the same rail.

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

There's an issue with your measurements, in post #6 you said " PP5V_S5 = 5v", in post #14 you said " VREG5 = 0.8V". They're the same rail.

Sorry about..I now checked over PP5V_S5 and it's reading 0.8v

[platinumsteel]

Re: Macbook pro 2012 820-3115-B Greenlight no Power on

Resistance on
L7220 = 0.138V
=0.812k

L7260 =0.440V
=3.425K and climbing

Below are U7941 and U7200 voltages

U7941

Pin1 PP3v42_G3H 3.42v
Pin2 SMC_PM_G2_EN 3.42v
Pin3 P5V3V3_Reg_EN 3.5v
Pin4 P3V3S5_EN_L_R 0v
Pin 5 GND
Pin6 PP3V3_S5 0v
Pin7 S5PGOOD_DLY 0v
Pin8 S5_PWRGD 0v
Pin9 GND

U7200

pin1 P5VS3_ENTRIP =0v
pin2 P5VS3_VFB =0v
pin3 P5VP3V3_VREF =2.6v
pin4 P5VP3V3_REG3 =0v
pin5 P3V3S5_VFB =0v
pin6 P3VS5_ENTRIP =0v
pin7 P3v3S5_V02 =0v
pin8 P5VP3V3_REG3 =0v
pin9 P3V3S5_VBST =0v
pin10 P3V3S5_DRVH =0v
pin11 P3V3S5_LL =0v
pin12 P3V3S5_DRVL =0v
pin13 5V3V3_REG_EN =3.7v
pin14 P5VP3V3_VREF =2.7v
pin15 GND
pin16 PPBUS_S5_HS_OTHER_ISNS =12.58v
pin17 PP5V_S5 =0.865v
pin18
pin19 P5VS3_DVRL =0.861v
pin20 P5VS3_LL =0v
pin21 P5VS3_DRVH =0v
pin22 P5VS3_VBST =0v
pin23 P5V3V3_PGOOD =0v
pin24 P5VS3_VO1 =0v
pin25 GND