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820-00045a No Power on any power lines Retina MacBook 2015

S

shassh

New member
Hi all,

I have a 2015 Macbook A1534 Retina which started off having issues charging and receiving power from charger - now wont charge or receive 14.5v.

I have tried another cable and charger with no luck, the little LED on the board (next to the battery connector) does not light up with no power going to any of the rails, as opposed to the common stuck on 5v issue - this is not that. I am getting 0 volts.

After leaving the battery disconnected a while and reconnecting, the little juice which was left in the battery allowed for a very brief on time, showing the battery low symbol, and the power LED was on without being plugged.

As a test I plugged in a normal usbc 5v charger and I get the power light on, and I get voltages through the motherboard. However its not enough to charge an extremely dead battery. The screen did show the charging symbol but I think was not enough power to charge and drained the battery completely.

I know that the motherboard and charger need to negotiate the power (5v or 14.5v), it seems like it knows to turn off 5v, but somehow unable to turn on 14.5v, unlike the common stuck on 5v issue.

I’ve checked for shorts, i cannot see anything obvious, nothing getting hot, but no LED light, no power in any rails.

Anyone have any experience on something similar?

All help will be greatly appreciated.

Thanks in advance.
 
S

shassh

New member
Just to add, I have tried another USBc port, which gave the same results. Checking the power output from the charger through the port (disconnected from the mother board) i still get 0 volts through +VBUS line on USBc, I am assuming the charger gives 0 volts until it knows which power to switch to?

Could it be the charger is not "detecting" its being connected to something?
 
2informaticos

2informaticos

Administrator
Staff member
Test the board with charger only, battery disconnected.
If board works on 5V cable, then the issue should be on the input stage, or charger itself.
The USB-C charger doesn't give voltage without load.
Did you check F4700?
 
S

shassh

New member
Hi thanks for your response.

I have tested the board with charger only, 2 different chargers (one new), and 2 different USB-C ports (one new). Still no power.

F4700 checked and is fine, no short to ground either

Its almost as if the motherboard/charger are not detecting each other.

Anything I could check further?

2informaticos said:
Test the board with charger only, battery disconnected.
If board works on 5V cable, then the issue should be on the input stage, or charger itself.
The USB-C charger doesn't give voltage without load.
Did you check F4700?
Click to expand...
 
S

shassh

New member
Ive done a few tests, apologies for being a noob.

F4700, C4750, C4755, R47551, R47561 = all seem fine, though 0v
D4750 = fine, though I havent removed it - it looks fine - 0v

Q4750 = looks okay, but is the top of it (the shiny layer - I was curious) supposed to be on PPDCIN_G3H? I checked the top of Q4750 with R4750 pins on diode mode:

PPDCIN_G3H = 0
PPDCIN_E85_SS = 062

Cheers
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
"D4750 = fine, though I havent removed it - it looks fine - 0v"
I don't exactly understand you...
I meant to measure between D4750 pins, in diode mode.

"PPDCIN_G3H = 0"
What this means?
Can't be short (diode mode), as it works on 5V USB cable.
And I didn't ask for voltage there; you already posted no voltage present.

"PPDCIN_E85_SS = 062"
Is this diode mode?

I hope you disconect charger and battery when check continuity (diode mode/ohm scale) on the board...
 
S

shassh

New member
All checks were done with charger and battery disconnected. Following readings in diode mode.

D4750 = 682, with no connectivity with probes the opposite way around. So assume diode is good.
PPDCIN_G3H rail = 0, full connectivity with the top on Q4750 - I'm not sure if that's normal or not.
PPDCIN_E85_SS rail = 062, with the top on Q4750 - again I'm not sure if that's normal or not.

Cheers
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Post power rails to ground on diode mode; not to other point.
Test Q4750 on diode mode between its pins, not to ground.
 
S

shassh

New member
I was just a bit confused why the top of Q4750 was conductive to those lines - still learning.

Follow lines tested with diode mode to ground:
PPDCIN_G3H = 504
PPDCIN_E85_SS = 504
PPDCIN_E85_SS_DIV = No reading.

Q4750 pin 1 and pin 4 = 683
Q4750 pin 1 and pin 2 (and pin 3) = 723
Q4750 pin 4 and pin 2 (and pin 3) = 061

Hope that's more informative. Cheers
 
S

shassh

New member
I'd like to ask, looking at the schematic suggests SLG4AP645AV chip, however on the chip on the board it has 645BV D5002 URD stamped on it. Will a SLG4AP645AV work on it or will I need specifically SLG4AP645BV, B being a lot harder to source.

Cheers
 
2informaticos

2informaticos

Administrator
Staff member
No idea.
You can try it if is the same size.
Sometime digits termination reffers to package size and type, temperature...
 
S

shassh

New member
Just another update,

So changing the U4700 IC did fix the issue, for a little while then it died again. Changed for the second time and it's still going however usb storage devices are not recognised.

The original usbc charge/data cable seems bad to me, when I connect my mobile phone the MacBook, the MacBook charges from my phone with cable connected one way, but not the other. The phone doesn't show anything. Tried a new cable and the MacBook doesn't charge in any orientation, but nothing happens. Very odd.

Is it possible that the original cable was an issue, which has caused the USBC port to malfunction and cause U4700 IC issue?

I checked the port, I seem to have full connectivity to ground in what I believe is pin A5 CC1, but not on pin B5 CC2. This seems odd to me.

Any vitals to check for no usb detection?

Either way I have a new USBC port on the way.

?????
 
2informaticos

2informaticos

Administrator
Staff member
Disconnect USB-C port from logic board.
Then check resistance for C4706/07.
If still short on any, bad solder under U4700.
Not common bad capacitor, but you can check them, just in case.
CC1/2 are used to detect external device type.
 
S

shassh

New member
Just had a look, no short on either capacitor.

Maybe it's the SBU1/2 pins on the port. I'm not sure. But I disconnected the port fully and tested the pin CC1/2 or SBU1/2 (I can't tell which it is) .One of these is short to ground without anything connected to the port .

I checked voltages on f4700 I get ~14.4v, but if I spin the cable around I get ~5v.

Oh, and my sound card 820-4940-B started crackling on speakers and died. Headphones still work.

I hate this MB :-|
 
S

shassh

New member
Even weirder, I thought just in case there are bad solders I will reflow u4700, put everything back together. Same issue with the cable giving 14.5v one way, but it's the OTHER way around (I initially marked it so I knew).

What the hell is going on...
 
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