Apple Mac Air A1466 820-000165

[smic717394]

Hi everybody, first of all, Happy New Year to all the members of this community. I need a bit of help, I have a MacAir A1466 with a motherboard 820-000165-A. It was dusty like hell, but no water damage. The only point there it had a bit of green stuff maybe condensation it was on the SPI connector J6100 on pin 1 and 3. I cleaned the connector and the board and it looks mint, the water indicators are white and nothing that will scream bad.

What it does is, when connecting the charger with everything disconnected, the light goes green then orange, that its normal behaviour, the consumption is 0.030A. L7130 has 8.6V which means the SMS is starting, The line P2V42 is 3.4V. If I connect the battery, it will charge the battery and goes green when charged. Checking with the thermocamera the SMC gets a bit warm nothing out of the ordinary, and the ISL6259 - U7100 gets warmer about 40 degrees, but this is the battery charging IC and since its charging I assume its OK.

The CPU coils have 0V, and very low resistance, I can't remember exact value but around 0.5ohm.

What other rail should I check? I´m thinking a bad SMC. Please help.

[mon2]

With PPBUS_G3H (L7130) @ 8v6, the SMC is running.

Review this website:

PM SLP S4 L Timing - IT-Tech Online

MacBook SMC Circuit and PPBUS_G3H voltage adjustment - IT-Tech Online

[smic717394]

Thank you. I´ll have a look. But I have the bad feeling its the CPU, like I said it was very dusty. The cpu resistance on the 2 coils is 0,5ohm, my leads without anyting are 0,25ohm, Injecting 0,8V on either of the 2 coils the voltage drop to 0,5v and the current jump to max IIf i limit to 1A will jump to 1A if I limit to 2A will jump to 2A and the cpu not pch will get hot on one corner. Maybe is normal.

[mon2]

When you say 0,5 ohms - is this the resistance to ground? This is of concern and sounds quite low for the CPU but do wait on feedback from others.

[smic717394]

Yes, measuring the 2 cpu coils to ground shows 0,5 ohm, injecting 0,8v on this coils, I het voltage drop to 0,5v. I will try tomorrow to remove this 2 coils so there is no continuity to the cpu, see if the 1,8V is generated on the board side.

[smic717394]

The RTC is 3.3v but the cpu vcore nothing, I removed the 2 coils, still no voltage, but measuring the resistance with the coil removed I get on the cpu side 0.5ohm and on the other side on Kohm range, my leads are 0.2ohm, so I think cpu is busted, but just wondering even if the cpu is dead removinf the 2 coils there no short so I should get on one side of the coil 0.8 or whatever the vcore voltage is.

[reformatt]

0.5 ohms is too low for CPU Vcore on these. They normally measure 10 ohms or more depending on the CPU type. So you either have a shorted cap or CPU. It's rare for me to see shorted Vcore though without the PCH also being shorted as well (check L7630 resistance). You won't see any voltage on Vcore without the coils fitted, as that in conjunction with the MOSFET's switching is what produces the voltage.

Most boards with this kind of fault will initially try to go though the power sequence and go back to the S5 state when there is no feedback from the PCH/CPU to the SMC. So you need to check voltages when first powering on.