Macbook Pro 2012 820-3115 Missing PP5V_SUS

[platinumsteel]

hi guys gooday i have a macbook pro 820-3115 that i wanted to get up and running for personal use. it's stuck on 20 milliamps . It has green light.I measured some voltage rails and am stuck on PP5V_SUS missing. Hoping you guys can guide me further on other things to check thx.

PPBUS_G3H= 12.56v
PPBUS_S5_HS_COMPUTING_ISNS= 12.56v
PP3V42_G3H= 3.4v
PPVRTC_G3H= 3.3v
PP5V_S5= 5v
PP5V_SUS= 0v
PP5V_S3= 0v

PM_SLP_S4_L = 0v
PM_SLP_S5_L = 0v

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

What are the voltage to ground readings for the following?

PP5V_S5_P5VSUSFET

P5V_3V3_SUS_EN

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

What are the voltage to ground readings for the following?

PP5V_S5_P5VSUSFET

P5V_3V3_SUS_EN

PP5V_S5_P5VSUSFET = 5v
P5V_3V3_SUS_EN = 0v

Not sure am doing anything right.But trying to anticipate where you might ask me to check next.

U7940 outputs P5V_3V3_SUS_EN ?
PM_SLP_SUS_L 3.3v
SMC_BATLOW_L = 0V

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

What is the voltage to ground of

SMC_RESET_L ?

ALL_SYS_PWRGD ?

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

What is the voltage to ground of SMC_RESET_L ?

SMC_RESET_L = 3.4v

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Check ALL_SYS_PWRGD as well.

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Check ALL_SYS_PWRGD as well.

ALL_SYS_PWRGD = 0v

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

So at least one of the power rails is not working.

It is bringing this logic status to LOW. Every power good needs to be HIGH to indicate the power rails are working.

The attached is the logic 'AND' gate built up from the power good signals.

If each input is HIGH, this signal line is HIGH = good to go.

If even one of the power good signals is low, then this signal will be LOW. A low on power good means the power rail is not working.

To debug this, you can flux and remove the series resistors on this tree. One by one, confirm the power good signal is OK and is NOT low.

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Not to sure i understand what you mean. Do you mean remove the series resistors on left of U7960 according to the schematic one by one.And like each time i remove one resistor check to see if ALL_SYS_PWRGD returns ?

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

No. See above the purple highlighted signal that was posted.

That is the output 'AND' tree from each power good rail.

Remove each resistor with flux. Keep track of which parts you are removing. Then apply only one at a time back onto the board.

If even one signal is low, this output will be low. We need to know which one is low.

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Okay just finished testing.I removed all resistors first checked for all_sys and nothing.So each one i put back in.I tested right after for all_sys and 0v for each time i put it in.All resistors are back in now.

[reformatt]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

SMC_BATLOW_L = 0V

Wasting your time until your sort this out. This level only goes high from the SMC when you have a 85W Magsafe 1 charger. It determines that via the one wire circuit.

I have a 60W genuine Magsafe 1 charger for the older Mac's and this line stays low on those. Only goes high with 85W chargers.

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Wasting your time until your sort this out. This level only goes high from the SMC when you have a 85W Magsafe 1 charger. It determines that via the one wire circuit.

I have a 60W genuine Magsafe 1 charger for the older Mac's and this line stays low on those. Only goes high with 85W chargers.

Well yeh i guess.Cause i only have a original 85w charger. And on my bench PSU am using a 85watt L- Tip cable. and i checked SMC_BATLOW on my other identical working board and yes it's 3.2v on that line.
Think i will try to get my hands on an SMC from a donor and replace it and see how it goes or if anything changes.

[reformatt]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

There is a hack to bypass it if your SMC is bad. Fit a 0 ohm resistor to R7917, remove Q5040 and short pads 1 and 2 of that transistor.

[mon2]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

Re:post #11

If you removed all power good resistors and still had a low, this means your pull-up voltage at very top of the tree is missing.

Check the pull up resistor and the voltage on the high side. Is it present?

[platinumsteel]

Re: Macbook Pro 2012 820-3115 Missing PP5V_SUS

There is a hack to bypass it if your SMC is bad. Fit a 0 ohm resistor to R7917, remove Q5040 and short pads 1 and 2 of that transistor.

Okay pal thanks a lot for the hack.It definitely works but well The board boots up I get CPU_VCORE . The boards stays on for like 8 seconds then goes off then back on and stays on for 8 seconds then goes off and stays stuck at 20 milliamps. One weird thing is i don't get fan spin. swapped fans but same. Possible there is something wrong elsewhere as well? Thinking i should not go further till i get a good SMC. lol

@mon2 Not to sure which pull up resistor to check.And the voltage on the high side.