820-3330 green/orange light on magsafe, no fan spin

[stefMT]

Hi,

I have been watching Louis' videos for some time now and finally got around to trying to troubleshoot what's wrong with my 2012 15" Unibody Macbook Pro.

I am new to this so I don't really know where to start diagnosing. I have some donor boards which I can take components off of.

One thing to note is plugging in the charger, even for 5 minutes, the board gets really hot which makes me believe I have a short somewhere.

Can anyone please provide some tips as to where to start from so I can hopefully find the root of the problem?

 

[stefMT]

PPCHGR_DCIN = 16.8v
PP3V42_G3H = 3.41v
PPBUS_G3H IS 12.02v and rising slowly .01 steps
PPVRTC_G3H = 3.35v
PP5V_S3 = 5.07v
PM_SLP_S3_ = 3.32v
PP3V3_S0_PCH = 3.33v
PP5V_S5 = 5.07v
PM_SLP_S4_L = 3.33v
MEMVTT_EN = Not present
MEMVTT_EN_L = 5.07v
PP3V3_S0 = 3.34v
PP5V_S0 = 5.07v
PP1V8_S0 = 1.80v
PP1V05_S0 = 0.09v

 

[aprendiz]

this measures are with charger only? or battery + charger.....
Your charger is 85W original????
PP5V_S3 not present but PP5V_S0 present???? Something is wrong here...

 

[stefMT]

this measures are with charger only? or battery + charger.....
Your charger is 85W original????
PP5V_S3 not present but PP5V_S0 present???? Something is wrong here...

Charger is 85W original charger that came in the box.
Measures with both charger and battery connected with orange light showing on the charger

 

[stefMT]

No Title

So I decided to take the board out of the chassis. About time, yes I know..

I found a burnt chip indicated in the photos

Can someone indicate what could be the cause? As I have a donor board and can swap it out but I don't want to burn that one as well if there is something else wrong on the board

 

[stefMT]

My initial problem was that I knocked off a resistor which is connected to a capacitor which connects to CPUVCCIOS0_LL which are 3 of the pins on the chip burned. That resistor is now back in place. Could the problem have something to do with that?

Since the resistor was knocked off there shouldn't have been any current flowing. So I don't believe the chip got more voltage or amperage than it's used to.

 

[2informaticos]

"Since the resistor was knocked off there shouldn't have been any current flowing."
Wrong asumption, that resistor is from bootstrap circuit of high-side MOSFET (Q7630); it got burnt because of high RdsON.
N-channel MOSFET requires 5V G-S (PWM signal amplitude) for properly working.
If bootstrap circuit doesn't work, the amplitude is very low, increasing RdsON a lot...

Remove burnt MOSFET and check low-side one (Q7635) for short.
I recommend you to change U7600 too.
Be sure that R7630 has correct 0ohm value and C7630 is still in place.

 

[stefMT]

How do I check a mosfet for short? I have never done this before
Also the R7630 when testing on Ohm mode 200 it comes up with 00.2 or 00.3 is this good?

Thank you for taking your time to help me

 

[2informaticos]

Less than 0.5ohms is OK.
That low value is because of multimeter leads resistance; you will never get 0.0ohms.

 

[dukefawks]

High side FET on VCCIO is shorted out. This will have killed the CPU and or PCH already. This board is RIP.

 

[stefMT]

High side FET on VCCIO is shorted out. This will have killed the CPU and or PCH already. This board is RIP.

Is this a possibility or 100% sure? How can I test to see if the CPU or PCH are actually burned? Thanks

 

[dukefawks]

I have never had a CPU survive this so unless you have time to waste this is a very unlikely repair. There is no way to test the CPU besides fixing the board and hoping it works.