Macbook A2289 820-01987

[sourcensolutionsonline@gm]

Hello,
Looking for some help here , This macbook came in dead , customer stated that it was charging and left connected overnight then the next day the computer was not coming on , I opened it and found U4910 and U4920 were both fried to ashes, When i ran a quick Diode mode only in that area I found that power rail PP1V8_MESA was fully shorted to ground , I then removed and replaced U4910 And U4920 and the short was gone , but the computer is still not booting . I measured PPBUS_G3H in diode mode and I got a value of 0.388 and in voltage mode I am getting 12.25 V but my amp meter is still reading 5V I have not changed The USB Controller chips U3100 OR U3200
Please advice that would be highly appreciated.

Thank you very much

 

[2informaticos]

Is the machine recognized in DFU mode?
Did you test the board alone on the desk?
At leats try disconnecting audio flex.

 

[sourcensolutionsonline@gm]

I have not done any DFU mode test yet , I did test the Board alone by removing it completely out . When I connect it to my DC POWER SUPPLY , its consuming 0.47 milliamps. Let me know if there s any other test to run please.

 

[2informaticos]

Pretty sure you can't measure 0.47 milamps (470 microamps).

470 miliA means there is significant consumption; you probably get voltage on various big coils.

 

[sourcensolutionsonline@gm]

I am using this device AY-3200 boot cable , when I connect it , I get 0.47

 

[2informaticos]

No need to use such bold letters; is better to know what that thing shows.

Didn't get time yet to try DFU?

 

[sourcensolutionsonline@gm]

no , do you have any tutorial on how to get that macbook in dfu mode? Sorry about the bold letters , it was when i copied the name of that device and pasted it here it came out like , sorry about that.

 

[2informaticos]

Follow all the steps in tutorial...

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

 

[sourcensolutionsonline@gm]

I have tried all the options but its not going into DFU mode, What would you suggest ?

Thank you very much.

 

[2informaticos]

First, what means 0.47?
Do you think about Volts, or Ampers.

Don't you have a classic USB-C meter?

https://es.aliexpress.com/item/1005004496495823.html?spm=a2g0o.productlist.main.5.49fd1c33ANZZRW&algo_pvid=348ed83f-bf1c-47ca-9987-8764b8361bbf&algo_exp_id=348ed83f-bf1c-47ca-9987-8764b8361bbf-2&pdp_ext_f=%7B%22sku_id%22%3A%2212000031928424644%22%7D&pdp_npi=2%40dis%21EUR%2112.21%216.47%21%21%21%21%21%402100b88516751834968038109d06fd%2112000031928424644%21sea&curPageLogUid=9xoVEkwyR1wz

 

[sourcensolutionsonline@gm]

the 0.47 ampers , that's what i got on the small blue device, I do ave the USB-C meter and on that one i got 5.08 Volts 0.008 Ampers and 0.000 watts

 

[2informaticos]

How can you explain one meter shows 470 mA and the other only 8 mA?
Use the normal one and forget that blue bulshit.

Check AWAKE and SLPS2R voltages; the small coils around U7800.

 

[sourcensolutionsonline@gm]

Yes, I put the Blue stuff on a side ,
I checked the voltages of The small coils around U7800,

The AWAKE Voltages

PPVDDCPU_AWAKE = 0.589
PPVDDCPUSRAM_AWAKE =0.00
All the SLPS2R voltages = 0.000
Does that mean U7800 is dead?

 

[2informaticos]

Compare their diode mode readings with good board.

"All the SLPS2R voltages = 0.000"
Even 0V8?
That is an LDO.
Check R7900 and diode mode to ground on both sides.

 

[sourcensolutionsonline@gm]

Yes even 0V8 =0.000

for R7900 One side PP3V3_G3H_PMU_VINRTC_R = 0.493
and the other side PP3V3_G3H_RTC = 0.340 in diode mode to ground.

 

[2informaticos]

So R7900 is burnt, as you don't get same reading.
I expected you to check its ohm value first...

 

[sourcensolutionsonline@gm]

The reading of R7900 in Ohm is 20

 

[sourcensolutionsonline@gm]

So you conclude that R7900 is burnt as values are not the same on both sides.

 

[sourcensolutionsonline@gm]

Any Suggestions?

 

[2informaticos]

Didn't change it yet?
Must be 0 ohm (short).