Macbook A1502 820-4924-A No power

[orion78fr]

Hi !

Someone brought me a Macbook A1502 with no power & no green light on charger. Opened it & no liquid damage, good start.

It had a short on the capacitors just above the battery connector, so I thought it would be simple. Injected voltage, saw a heat spot on the back of the board, and yeah, C6432 was blown (rather catastrophically, fused with the pad, but whatever, it's audio so it's not the most important for now), and removing it cleared the short.

However, still no green light... Pull up my thermal camera again and OMG Q7010 & R7020 are at > 100°C !

Here, I don't know where to look, as I'm clearly not an expert on Macbooks, but here's what I know :

• The only other thing that heats up is U5000 (the SMC if I'm not mistaken), but only 30°C, so I think it's normal operating temperature.
• Q7010 & R7020 are not getting hot immediately, only like 1s after plugging the charger (probably after the SMC kicks in ?)
• There is no short after R7020 (it reads 100kOhm to ground, so it seems OK)
• Caps around U7100 not shorted, R7121 & R7122 not pulled to ground by U7100 (read that it can do that)
• PPBUS_G3H is around 2V, PPDCIN_G3H is around 15V (probably voltage drop due to the amperage drawn)

Please tell me where to look, I'll take measurements, but can't let the charger for long to get voltages because of the heat produced.

[mon2]

Re: Macbook A1502 820-4924-A No power

PPBUS_G3H is around 2V

Remove fuse F7140. Power up again.

Meter in dc volts mode (20 volts or higher).

What is the voltage to ground of the pcb pad for F7140, pin #1 (PPBUS_G3H)?

Remove all power. Meter in resistance mode.

Measure the resistance to ground of the pcb pad for F7140, pin #2 (consumer side of the PPBUS_G3H rail).

Post all measurements and the meter scale used for the tests.

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Remove fuse F7140. Power up again.

Still getting hot when powered on.

Meter in dc volts mode (20 volts or higher).

My voltmeter has an auto scale mode, so shouldn't be a problem.

What is the voltage to ground of the pcb pad for F7140, pin #1 (PPBUS_G3H)?

1.230 V, slowly decreasing as the board gets hotter.

Remove all power. Meter in resistance mode.

Measure the resistance to ground of the pcb pad for F7140, pin #2 (consumer side of the PPBUS_G3H rail).

~15 MOhms, slowly decreasing.

The producer pad is weird though, 400kOmhs slowly decreasing to 2kOms in 15 seconds, then jump back to 400kOmhs.

[mon2]

Re: Macbook A1502 820-4924-A No power

Fault is in the producer side of the ppbus_g3h rail.

Remove all power. Meter in resistance mode.

What is the resistance to ground of F7140, pin #1 pcb pad?

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Fault is in the producer side of the ppbus_g3h rail.

That's what I guessed

Remove all power. Meter in resistance mode.

What is the resistance to ground of F7140, pin #1 pcb pad?

As I said, the producer pad is weird, 400kOmhs slowly decreasing to 2kOms in 15 seconds, then jump back to 400kOmhs and loops.

[mon2]

Re: Macbook A1502 820-4924-A No power

Am confused.

~15 MOhms, slowly decreasing.

The producer pad is weird though, 400kOmhs slowly decreasing to 2kOms in 15 seconds, then jump back to 400kOmhs.

The ISL side is ~15 Mohms ? That is fine.

The other side of the fuse is the consumer side of the power rail.

[mon2]

Re: Macbook A1502 820-4924-A No power

What is the voltage to ground of PPDCIN_G3H_CHGR ?

You can measure @ C7130 (+) tab.

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Am confused.

Pin 2 (PPBUS_G3H) is 10 MOhm
Pin 1 (PPVBAT_G3H_CHGR_REG) is the one fluctuating between 400 kOmh & 2 kOhm

What is the voltage to ground of PPDCIN_G3H_CHGR ?

You can measure @ C7130 (+) tab.

PPDCIN_G3H_CHGR is 14.6 V

[mon2]

Re: Macbook A1502 820-4924-A No power

PPDCIN_G3H_CHGR is 14.6 V

That sounds too low. Using an official and proper rated power adapter?

What is the voltage to ground of PPDCIN_G3H ?

This is the INPUT voltage to the ISL6259 @ U7100. You can measure @ F7005.

What is the voltage to ground of PP3V42_G3H ?

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Sorry for the delayed response, had to work on some other boards.

That sounds too low. Using an official and proper rated power adapter?

It's the official 45W Magsafe 2 power adapter (A1436, 14.85V 3.05A) that was in the box my customer brought me, so I guess it's the correct one. Tested with another A1436 and an USB charger with a magsafe adapter (that works on my wife's macbook air) and got the same result.
Remember that Q7010 & R7020 are getting really hot, over 100°C rapidly, so the boards probably draws a lot of amps, and that probably makes the voltage lower a little.

What is the voltage to ground of PPDCIN_G3H ?

This is the INPUT voltage to the ISL6259 @ U7100. You can measure @ F7005.

F7005 voltage is 15.07V (both sides)

What is the voltage to ground of PP3V42_G3H ?

PP3V42_G3H (on test point left of D7005) is 0.52V, which seems way too low.

[piernov]

Re: Macbook A1502 820-4924-A No power

https://support.apple.com/en-us/HT201700

[orion78fr]

Re: Macbook A1502 820-4924-A No power

https://support.apple.com/en-us/HT201700

Oh... So if I read correctly A1502 should be an 85W charger and be 20V 4.25A ? It was nicely packaged in the original box and still had plastic wrap on it so I thought it was the original one...

So, it won't work with the 45W one ? Not even give a green / orange light or attempt to boot but charging slow / not charge ?

[mon2]

Re: Macbook A1502 820-4924-A No power

I think you have assorted issues on this board - including use of a wimpy power adapter. The power adapter should offer a higher voltage than what you are measuring (assuming that your meter is accurate / with fresh batteries).

Measure the voltage to ground on EACH pin of D7005 diode. Does this dual anode diode pass through the voltage present on pins 1 / 2 - diode will select the higher of the 2 voltages to power this regulator.

If you DO NOT see the proper voltage on pin # 3 = output of this diode, then power down.

Remove all power -> meter in resistance mode.

Measure the resistance to ground on pin # 3 of this diode D7005.

Post all measurements.

[reformatt]

Re: Macbook A1502 820-4924-A No power

A 45W charger will give you magsafe light green/orange, but the board definitely won't start. Just confirmed it with a 4924 board on the bench and a chipmunk USB. You need at least a 60W charger for them to even try to boot.

If you have the magsafe light, then you must have PP3V42_G3H.

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Measure the voltage to ground on EACH pin of D7005 diode. Does this dual anode diode pass through the voltage present on pins 1 / 2 - diode will select the higher of the 2 voltages to power this regulator.

If you DO NOT see the proper voltage on pin # 3 = output of this diode, then power down.

D7005
1 PP18V5_DCIN_CONN_R 3.26V
2 PPBUS_G3H_R 0V
3 PPVIN_G3H_P3V42G3H 2.8V

Is that normal that it's so low in input of D7005 ? Voltage drops from 15V to 3.3V between the pins of R7020, but I think it shouldn't. Is the resistor bad ? My meter reads 46.9 Ohms in resistance mode, but I don't know, maybe it does something weird with voltage.

Remove all power -> meter in resistance mode.

Measure the resistance to ground on pin # 3 of this diode D7005.

4Mohms dropping to 50 kOhms in 11 seconds then cycling

A 45W charger will give you magsafe light green/orange, but the board definitely won't start. Just confirmed it with a 4924 board on the bench and a chipmunk USB. You need at least a 60W charger for them to even try to boot.

I see, I told to the owner and he will look for a proper 85W charger.

[orion78fr]

Re: Macbook A1502 820-4924-A No power

I read somewhere that R7020 overheat was probably something around U7090.
R7095 R7096 looked good, C7094 not shorted...
Checked diode mode to ground on L7095, 0.002, weird. Resistance mode, 2 Ohm.

Okay then, let's inject voltage with bench power supply to see what's get hot.
1V, only drawing .5A... Maybe not enough ? 2V, drawing even less, .2A.
Only things getting warm is U5000, in the 30°C, so I guess normal.

And guess what ? Putting charger back, nothing gets warm, and get a freaking green then orange light ! What the actual hell ? Going to solder back the F7140 fuse I unsoldered earlier and see what happens...

[mon2]

Re: Macbook A1502 820-4924-A No power

Pin #1 of D7005 is with the wrong voltage. Check again if that voltage is now restored.

[orion78fr]

Re: Macbook A1502 820-4924-A No power

I get 14.25V now on pin 1 of D7005... plus an orange light...

[mon2]

Re: Macbook A1502 820-4924-A No power

What is the ppbus_g3h voltage?

Is the laptop booting?

[orion78fr]

Re: Macbook A1502 820-4924-A No power

Yeah it boots, but not with the mac adapter, only with my Nintendo Switch adapter with an USB to Magsafe 2 adapter.
I don't know if battery is super flat or not recognized yet.
I still have to restore the pad and solder C6432, but will do that tomorrow, it's 4:30 AM for me x).