820-3126 none usb port works

[andrespi]

Hello, This imac, no usb ports works, I have measured

PP3V3_S3_USB_HUB=3.3v
VBUS IN ALL PORTS USB=5V

The strange thing that does not turn on light when I connect usb mouse, It should turn on if it has 5v or I'm wrong

What measurements do I do more?

 

[2informaticos]

First, test Bluetooth, Camera and SD card.
This can give us an idea about where to continue.

 

[andrespi]

bluethooth is not working, camera and sd I do not know why I have no way to test since mouse does not work

 

[2informaticos]

Any history available?

External USB ports, bluetooth and SD card go through USB Hub 1/2.
Camera goes directly to PCH.
If 5V present on USB ports, then check L4601/11/21/31 continuity and diode mode to ground.

You can remove and bypass U4650.
Check FAULTx* levels of U4600/20.

 

[andrespi]

l4601/11/21/31 all measure continuity, diodo mode in all 0.69. How do I bypass u4650?
L3559, C3543/42 are burned

 

[2informaticos]

Ooops, bad U3500, or adiacent cap; solved the problem.

 

[andrespi]

excuse me, a little sulfate on L3559, C3543/42 It was already eliminated but a problem persists. How do I bypass u4650? How do I measure with a multimeter or oscilloscope FAULTx* levels of U4600/20?

 

[2informaticos]

Forget U4650 at the moment.
You should get another port working at least.

Check if both U3500/600 get correct power.

 

[andrespi]

vdd =3.3v power in u3500 and u3600

 

[2informaticos]

Voltage is splited with two coils for each chip.
Did you check if all power rails are good?

 

[andrespi]

yes, I measured in the 2 coils of each chip

 

[2informaticos]

Strange to have both chips damaged, but you can try changing them from donor board.
Compare diode mode readings on USB data lines with good board.

 

[andrespi]

I have 820-2641 board good, I see the board the same.L4621, l4601,l4611 usb data modo diode 0.69 is the same valor than board 820-3126 board bad usb