A1466 Missing Vcore

[mcplslg123]

Logic Board:820-00165A

It turns on without display. Vcore is missing. Rest all voltage are there.

01.All_Sys_PwrGood-3.3V
02.P1V8S3_PGood-3.3V
03.P1V05S0_Pgood-3.3V
04.DDRREG_PGood-3.3V
05.P5VS4RS3_PGood-3.3V
06.S5_PGood-3.3V

Missing
01.CPU_VCCST_Pwrgd. R1931 Pin1 has P1V05S, pin2 is zero.Resistance on R1931,pin1 is 110 Ohms,PIn2 is 0.885K.
02.U7200,PIn1 VR_EN is missing. CPU_VR_Ready is present on R1955. Resistance Value of R1800 is good.

R1931 showed incorrect value and was rusted/frozen on CPU_VCCST_PGood side. I've restored the two pads and soldered 10K Resistor. MB doesnt turn on if R1931 is soldered. If i remove R1931,it turns on without Vcore.

Can U1930 be bad or i'm on wrong path??
U1930 measurements
PIn1-PM_SLP_S3_L-3.3V
Pin2-All_SYS_PGood-3.3V
Pin4-CPU_VCCST_PG-0V
Pin6-PP3V_S5-3.3V


Have'nt done anything apart from measuring rails/voltages and replacing R1931 .

Please advise how to move further. As said earlier, i dont have much knowledge on macbooks repair

[Askic]

Re: A1466 Missing Vcore

Hello mcplslg123,

please measure:
P3V3S0_EN and check whether you have 3v3_S0.
U8030 is a switch that transfer 3v3 _S5 to 3V3_S0.

When P3V3S0_EN is 3.3V, it will "move" 3V3_S5 to 3V3_S0

[piernov]

Re: A1466 Missing Vcore

PM_SLP_S5_L most likely pulsing with R1931 soldered. Check with oscilloscope.

[mcplslg123]

Re: A1466 Missing Vcore

Hello mcplslg123,

please measure:
P3V3S0_EN and check whether you have 3v3_S0.
U8030 is a switch that transfer 3v3 _S5 to 3V3_S0.

When P3V3S0_EN is 3.3V, it will "move" 3V3_S5 to 3V3_S0

P3V3S0_EN & P3V3S0-Both are present with R1931 unsoldered.

[mcplslg123]

Re: A1466 Missing Vcore

PM_SLP_S5_L most likely pulsing with R1931 soldered. Check with oscilloscope.

With R1931 soldered, there is nothing on PM_SLP_S5_L. Consumption on dc Supply starts with 0.0015amps and goes to 0.0026A. magsafe light goes from green to orange. With R1931 unsoldered, PM_SLP_S5_L is stable 3.3V. With R1931 unsoldered it turns on, consumption at 0.0150A with missing CPU_VCCST_PGOOD

[piernov]

Re: A1466 Missing Vcore

Set trigger to single shot rising edge at like 1V on the oscilloscope if you can't see the pulse right away.
(maybe 500us/div horizontal)

[lamo]

Re: A1466 Missing Vcore

check these lines: svid_clk, svid_data and vid_alert. you should have some impulses at svid_data on CPU pwm ic.

[piernov]

Re: A1466 Missing Vcore

Unrelated. SVID won't work if VCCST_PGOOD is missing.

[mcplslg123]

Re: A1466 Missing Vcore

@piernov, will check it. Btw, if it pulses what is the solution??

[piernov]

Re: A1466 Missing Vcore

https://logi.wiki/index.php/User:Pie....2C_what_do.3F