Macbook A1708 - 820-00840 20v 50ma

[mon2]

Re: Macbook A1708 - 820-00840 20v 50ma

Next measure the resistance to ground of the pull-up resistor voltage rail.

This is on the other side of the same resistors.

Concern is if the 3v42 rail is shorted.

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

Resistance of the same 2 resisstors but second pad is 2Mohms and falling down. Should i inject 1V to one of this pads (SMBUS_SMC_5_G3H_SCL or SMBUS_SMC_5_G3H_SDA) ?

[mon2]

Re: Macbook A1708 - 820-00840 20v 50ma

No. Resistance is high so injection will not work. Measure if the voltage is stable here or not at 3v42.

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

Yes voltage on other pad of these two resistors (R5380 and R5381) is stable 3.42V

[MuertoGB]

Re: Macbook A1708 - 820-00840 20v 50ma

10ohms is normal for a CPU on the 00840. What concerns me is 350ma is in the realm of running current without a battery. However there are other important rails which need to be checked.

Check resistance and voltage on:
PPVCCIO_S0G_R (IO Voltage)
PPVCCSA_S0G_R (System Agent Voltage)
PPVCCCPU Phase 1 and 2 (PH1, PH2)

Q8060 creates voltage for the PCH, so the resistance of the PCH is needed as well from L7900.

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

I was not able to find PPVCCIO_S0G_R only PPVCCIO_S0G
no voltage on any of these lines when charger connected (20V 0.05A)
PPVCCIO_S0G (IO Voltage) - 0V
PPVCCSA_S0G_R (System Agent Voltage) - 0V
PPVCCCPU Phase 1 and 2 (PH1, PH2) - 0V

resistance to ground :
PPVCCIO_S0G (IO Voltage) - on TP 1,8ohm
PPVCCSA_S0G_R (System Agent Voltage) - 10ohm
PPVCCCPU Phase 1 and 2 (PH1, PH2) - 6,3ohm

[MuertoGB]

Re: Macbook A1708 - 820-00840 20v 50ma

PPVCCIO_S0G is too low, it should be more in the realm of 50-60ohms.

You are right, it is only PPVCCIO_S0G, I was tired when writing.

[spidertnt]

Re: Macbook A1708 - 820-00840 20v 50ma

Hi All I've one MacBook A1708 that is taking 20v 0.05a

I've checked and there is short to ground on PPBUS_G3H but I'm not able to locate it.

I've injected voltage on F7000 (1V 3A) but it was taking only 0,2a.

I've checked also C6465 but it's ok (I've take it from board and test with multimeter) - also when it was removed short was still there.

Can you please help me what is causing the short ?

Had so many of these boards be the audio capacitors shorting...just need to test each one .

C6465
C6445
C6405
C6425
C6481

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

I've checked all these capacitors and they're all good

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

I've checked the board with thermal cam again and I noticed that there are 2 hotspots.

U5000 is getting warm and also something where U6990 (most probably this IC) both IC (U5000 and U6990) at the same time.

after checking this areas I've noticed that one Resistor R6993 is shorted at one side AGND_P3V3G3H (but I guess this should be ground)

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

any idea ?

[obelix24]

Re: Macbook A1708 - 820-00840 20v 50ma

ok it looks like that probably CPU is shorted as there are many Capacitors near CPU shorted (C101B, C101D, C101E, C101F, ....)
So probably only way is to reflow CPU but this will most probably not work

[MuertoGB]

Re: Macbook A1708 - 820-00840 20v 50ma

ok it looks like that probably CPU is shorted as there are many Capacitors near CPU shorted (C101B, C101D, C101E, C101F, ....)
So probably only way is to reflow CPU but this will most probably not work

I did say a few messages back that VCCIO is way too low. I'm pretty sure this is your issue. You stated it's less than two ohms, which is not correct. You should remove the VCCIO inductor and see which side the low resistance is coming from.