MacBook 12" A1534 2017 820-00687-B

[mferna14]

I am working on MacBook 12" A1534 2017 820-00687-B assuming that the logic board is same as 820-00244-B. It was not powering on. I did a ultra sonic cleaning of the motherboard since I saw some traces of liquid spill. Tested out of the casing, all worked fine & display was working 100% well. When I installed it again, no display. So I again was removing the logic board & while removing the keyboard connector I saw little smoke off the connector. I started to check the voltages again. 3.3volts is perfect but 5 volts rail fluctuates on & off on coil L7670 (PP5V_S4)., 5V come & goes again. I did not find any short to ground on this rail. Any tips or guidance will really be appreciated. Thanks in advance.

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Anyone there to help... Thanks

[mon2]

Re: MacBook 12" A1534 2017 820-00687-B

Remove the keyboard / trackpad cables.

Check the EN pin on U7650 - does it also toggle ON / OFF with the pulsing of this rail?

Check the components on pins 7 & 8 on U7650. Anything missing ?

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Thanks "mon2" will do so & report... thanks for the help

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Ok 'mon2"., on the EN1 pin of U7650 (PM_SLP_S5_L) the voltage toggles on & off, even on pin 7 & 8 same thing voltage toggles.. But EN2 (S5_PWR_EN) pin 21, here the voltage is constant 3volts, this is why I am getting the 3.3v perfectly. Next to check I think "PM_SLP_S5_L" from where it genereating or some rail. Please inform me.. Thanks

[mon2]

Re: MacBook 12" A1534 2017 820-00687-B

1) PM_SLP_S5_L is generated by U0500, ball BH14 - sheet 15/67 of the PDF.

2) What is the voltage on PM_SLP_S5_L ?

3) With the power off, battery removed, what is the resistance to ground on L7670, pin # 1 ?

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

2) What is the voltage on PM_SLP_S5_L ? nearly 2.9 & then drops
3) With the power off, battery removed, what is the resistance to ground on L7670, pin # 1 ? 350.5k ohms & its keep on decreasing ohms

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Do think the CPU got defective???

[mon2]

Re: MacBook 12" A1534 2017 820-00687-B

The CPU may be defective as reported by more seasoned techs on this forum but hate to believe it. It is a show stopper of an issue if true.

Our fancy BGA rework station should land next week and we are looking forward to complex repairs like CPU rework / reflowing. Has multiple HD vision cameras to perfectly align the balls once we clean the drop site.

2) What is the voltage on PM_SLP_S5_L ? nearly 2.9 & then drops

What is the voltage reading once this rail settles ?

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Thanks "mon2"
"What is the voltage reading once this rail settles ?" the voltages never settles & it keeps on toggling on & off...

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

Mr. "piernov" any thoughts on this repairs... Hope you can give me some good tips. Thanks in advance.

[Erat]

Re: MacBook 12" A1534 2017 820-00687-B

I know its an old post but did you manage to find what was it? I have the exact same problem pp5v_s4 make spikes every so.

[mferna14]

Re: MacBook 12" A1534 2017 820-00687-B

This was a 11" Apple laptop, you know I could not find the problem, eventually I purchase a new motherboard, got for $200, worth it. You look for a new motherboard too, very difficult to find where the problem would be. Thanks