A1707 no CPU Vcore

[megabitit]

Hello Guys,

I have an A1707 820-00281-A, that doesn´t boot, that has 19.5V and stays at 20mA current, and drops to 0mA. All major rails voltages are ok, but I have 0V on L7211. I'm thinking in replacing the U7210.

Can anyone help me?

[piernov]

Re: A1707 no CPU Vcore

If you only have 20mA you are probably missing more than just CPU VCore.
Please go down the list of power rails to check their voltage so we can understand what state the board is in. Also describe history of the machine (liquid damage, physical damage…) and confirm you are using a known good genuine Magsafe 87W.
And don't replace U7210, there is no reason to.

[MobileXT]

Re: A1707 no CPU Vcore

Do you have PPBUS_G3H?

[megabitit]

Re: A1707 no CPU Vcore

Thank you guys.

Yes, i do have PPBUS_G3H.

I´m measuring all the power rails, and i´ll post them hear today. If anyone can help me, i´ll be apreciated guys.

[megabitit]

Re: A1707 no CPU Vcore

Thank you piernov. I´m measuring all the power rails, and i´ll post them hear today. If you can help me, i´ll be apreciated.

[megabitit]

Re: A1707 no CPU Vcore

Yes MobileXT, i do have PPBUS_G3H.

[megabitit]

Re: A1707 no CPU Vcore

Good afternoon,

The board just stoped working. It has no liquid damages or anything else... just stop working.

Here are the measurements I got:

PPBUS_G3H = 12.58V
PPBUS_HS_CPU = 12.58V
PPBUS_HS_GPU = 12.58V
PPBUS_HS_OTH5V = 12.58V
PPBUS_HS_OTH3V3 = 12.58V
PPBUS_S4_HS_TPAD = 12.58V
PPVCC_S0_CPU = 0V
PPVCCSA_S0_CPU = 0V
PPVCCGT_S0_CPU = 0V
PPVCCIO_S0_CPU = 0V
PP3V3_G3H = 3.4V
PP3V0_G3H = 3.0V
PP1V2_S3 = 0V
PP1V2_S3_CPUDDR = 0V
PP1V2_S0SW = 0V
PP0V6_S0_DDRVTT = 0V
PP0V6_S3_MEM_VREFD0_A = 0V
PP0V6_S3_MEM_VREFCA_A = 0V
PP0V6_S3_MEM_VREFD0_B = 0V
PP1V8_SUS = Fluctuates between 1.4V and 0.5V
PP1V8_S4 = 0V
PP1V8_S3 = 0V
PP1V8_S3_MEM = 0V
PP1V8_S0 = 0V
PP1V0_SUS = Fluctuates between 0.6V and 0V
PP1V0_S3 = 0V
PP1V0_S0SW = 0V
PP3V3_S5_T139 = Fluctuates between 0V and 3.3V
PP3V3_S4_SOC_PMU = 0V
PP5V_S0_T139 = Fluctuates between 1V and 0.5V
PP3V3_S5 = Fluctuates between 0V and 5V
PP3V3_SUS = 0V
PP3V3_S4 = 0V
PP5_S4 = 0V
PP5V_S0 = 0.5V
PP3V3_S4_T151 = 0V
PP3V3_S0 = Fluctuates between 0V and 0.5V

Can anyone help?

[piernov]

Re: A1707 no CPU Vcore

Good afternoon,
PP3V3_S5 = Fluctuates between 0V and 5V

I assume that's a typo since PP3V3_S5 should only go up to 3.3V.

Also I don't see PP5V_S5 in this list (and some others but should not be relevant for now).

Measure resistance to ground on PP3V3_SUS and PP5V_S4.

[shaban]

Re: A1707 no CPU Vcore

PP3V3_S5_T139
never fluctuates constantly 3.3 volts

[megabitit]

Re: A1707 no CPU Vcore

Hello piernov.

the PP5V_S5 = Fluctuates between 0V and 5V

The resistance of the PP3V3_SUS = 3M Ohm
The resistance of the PP5V_S4 = 5M Ohm

The PP3V3_S5 = Fluctuates between 0V and 3.3V

I have no idea of what's causing this

[megabitit]

Re: A1707 no CPU Vcore

The PP3V3_S5_T139 = Fluctuates between 0V and 3.3V

[megabitit]

Re: A1707 no CPU Vcore

Does anyone has any ideas? What should I check now?

[sunny1234]

Re: A1707 no CPU Vcore

Have you solved the problem, if yes what have you done? If not, can anyone help here I have the exact same problem.

[meineiid]

Re: A1707 no CPU Vcore

Hi there,,

i have the same issue too

[josuecas]

Re: A1707 no CPU Vcore

replace u7800