Macbook A1466 820-00165-A - No Power

[orion78fr]

Hi, I'm scratching my head on this Macbook.

Last time I worked on it (October), it had a speck of corrosion on the back of the board that ate R2281 & R8131 (maybe some condensation on dust ?). I replaced these two by the same values and the board worked correctly for 4 months.

Done all tests from here with the board out of the case without any battery plugged in, only the power board, fan & the L cable that connects to J9500, to rule out anything plugged in.

Today, Charger LED is usually Orange but no signs of life at all.

PPDCIN_G3H_ISOL & PPDCIN_G3H_INRUSH is 14.97 V
CHGR_DCIN is 14.7 V
PP3V42_G3H is 3.420 V

PPBUS_G3H & CHGR_PHASE is 1.88 V

PPDCIN_G3H to ground is 43.3 kOhm
R7105 is 20 Ohm
I don't see any corrosion on the board.


Sometimes charger led is off or switching green and off and all the voltages are pulsing & PPDCIN_G3H stays at 1.7 V.
(I looked at repair wiki and "No PPDCIN_G3H when using genuine Magsafe" says it may be Q7180 but Q7180 is not leaking back to the input it seems)

As R8131 has something to do with charging (CHGR_VFRQ), maybe it has something to do with it ? It worked fine for 4 months and is under solder mask.


Do anyone know where to look to narrow down the issue ?

[reformatt]

Re: Macbook A1466 820-00165-A - No Power

With no battery, PPBUS_G3H should be at least 8.3V even if the SMC is dead. So Magsafe status is something you look at later. Genuine Magsafe charger problems would result in no PP3V42_G3H if that were the issue, and you say that is present.

If it is pulsing, and PPBUS_G3H is 1.8V, then likely you have a short on one of the rails. Check either side of F7140 resistance to ground, along with all the other coils in the machine. L7630 in particular, which is the 1.05V supply for the PCH. Should be 150 ohms or more.

[orion78fr]

Re: Macbook A1466 820-00165-A - No Power

On F7140, both sides to ground are 13 MOhm slowly decreasing.
200 kOhm on L3095 and L7701, 30 kOhm on L7520, 393 Ohm on L7630, 0.67 kOhm on L7430, 20 kOhm on L7560, 20 Ohms on L7310 and L7320, 63 kOhm on L7750, 1.04 kOhm on L2920.

It is a genuine 45W Magsafe 2 (A1436) I'm using to diagnose.

Often, no light on charger, PPDCIN_G3H around 1.7 V, jumping around to 4 or 7 V (but might be a rounding of my multimeter for a short jump to the full 15V), PPBUS_G3H is 1.389 V.
Sometimes, orange light, PPDCIN_G3H at 14.97 V, PPBUS_G3H at 1.6 V.

I tried with my bench power supply and a Magsafe adapter and I don't get the on / off pulsing (cause I don't have load detection to switch on), but same voltages (PPBUS_G3H at 1.6 V).

[reformatt]

Re: Macbook A1466 820-00165-A - No Power

Genuine Magsafe chargers use a load detection feature before they switch through the 18V. It's normally leakage back from the battery side of things that causes this to malfunction. Quick way to test is to connect battery only and check voltage on R7012. Should be 0V. If anything above that, I've had a leaky D7005, corroded R7180 or Q7180 cause that.

On the bench with only Magsafe connected, you should have 18V or so on R7012. If this is fluctuating, then test with a knock off charger since these don't use load detection. You need to work out if this a load detection or an ISL problem.

[orion78fr]

Re: Macbook A1466 820-00165-A - No Power

With only the battery (which is pretty flat I think, it reads 2.4V), I read 19.8 mV at R7012, I don't know if that's enough to be worrying.

With the bench power supply & no battery, I get the same as when the genuine charger is orange, PPDCIN_G3H at 14.97 V, PPBUS_G3H at 1.6 V, no fluctuation.

Edit : by the way, with the power supply it only draws around 15 mA, if that's of any significance

[reformatt]

Re: Macbook A1466 820-00165-A - No Power

Check around U7100 for corrosion or liquid damage. 1.6V for PPBUS_G3H is abnormal and likely an issue around the ISL if there isn't a short on the bus. Sometimes it can be a faulty ISL as well.

[orion78fr]

Re: Macbook A1466 820-00165-A - No Power

Aside from R7102 missing (which is normal I guess cause it's written as NO STUFF in the schematics), I don't see anything. I will try to resolder U7100 just in case, but it's probably faulty then.