Macbook Pro A2442 (820-02098) Stuck at 5V

[Instafixx]

Machine doesnt switch on. Stuck at 5V on 3 USB_C Ports.

No Voltage at PPBUS_AON and PP3V8_AON.

i didnt get any PPDCIN_AON as well.

THE display is broken and customer used it via a external display.

UG400 is reworked already before.

 

[2informaticos]

Check diode mode to ground at R5220.
Also check all fuses corresponding to PPDCIN_AON.

 

[Instafixx]

Diode Mode Reading PPDCIN_AON at R5220 is .549.

For Fuses - You need ohms reading across Pins ?

 

[2informaticos]

No, just check if all fuses aren't burnt (open).

 

[Instafixx]

No Fuse is burnt visibly - and Diode Mode Readings are same on all fuses.

 

[Instafixx]

F5200
F5201

Diode Mode Readings are 0.002

Resistance across Pins 0.8 Ohms.

Both Fuses Removed- PPBUS_AON is shorted.

I get 12.3V on C5250

Tried Injecting Voltage but nothing gets Hot.
Went Upto 5V.
With Such a Pure Short i think 2-3V would have been enough i think

I dont have a 10A PSU.

 

[2informaticos]

Set amp limit to max and start with 1V.
If PSU enters in protected mode, will not inject anything.

Also check if any coil gives the same reading in diode mode to ground.

 

[Instafixx]

No other Big Coils gave same value in Diode Mode.
I set the amps to max and inject voltage. But the PSU wont go above 1.8 -2V as the amp draw is max at that point.
Nothing gets hot.
The wire is very hot.

 

[Instafixx]

CR663 is missing from the board. [PPBUS_AON_SPRAMP_ABC_ISNS]

 

[2informaticos]

Use powerfull cables.
You need to heat something on the board, not the cables.

For example, if you get 4A at 1.5V, that means 6W, enough to detect heat.

 

[Instafixx]

I am using the same cables i use always. I am getting 5A at 2V - 10W is being injected and still nothing heats up.
The ground cable [Black] heats up.

Let me try with another set of cables .

 

[Instafixx]

Tried with a different set of cables sir.
I get the Max 5A at 1.2V now. Not going higher than that. Nothing heats up. Please guide

 

[2informaticos]

If PSU displays 5A, may be already in protection mode.
Stop at 4.5A, there should be enaugh heat to detect.
Use IR camera...

BTW, remove the CPU heatsink.
What is exact ohm resistance to ground at PPBUS_AON?

 

[Instafixx]

Exact Ohms Resistance to Ground is 0.8 Ohms.

You mean i should reduce the AMPs to 4.5A and keep increasing voltage ?

 

[2informaticos]

You can't control the injected current; didn't understand Ohm law yet?

Start with 1V and increase the voltage until get 4.5A.

 

[Instafixx]

That is excatly what i am saying. I am reaching 4.5A at around 1V with 1 set of Cables and 2V with another set of cables.

My PSU just got busted.
I have another 5A PSU. The same. I increased voltage till the AMP draw went upto 4.5A. Nothing gets hot at all.

 

[2informaticos]

"Use IR camera"

 

[Instafixx]

Hi , I Tried with 10A PSU as well. I reach 10A around 4V. UR700/30/60 area got a little warm but nothing hot enough. I Dont have a IR Camera.
Burnt my cables too in the process. I am not understanding what is happening.\

I tried removing UR700/30/60.

I also removed CR765/35/04.

Still the same short.