820-3787 USB and BT issues

[cwalex]

Hi,

I have a board that will boot from ASD flash drives but it won't boot from my USB 2.5" SSD macOS test drive. The other problem is that when the wifi card is connected, it won't boot. I'm guessing it's to do with the BT side. Tried with a known good card.

I also noticed that the USB controller test in ASD failed when I had my 2.5" USB SSD connected. At the same time, the screen was extremely flickery. I couldn't reproduce the behaviour again though.

This board has had liquid damage but it's been worked on before So there is flux and probe scrapes all over the place. Any help would be appreciated.

 

[2informaticos]

Check for low values on 3V3_S3/0 lines for WLAN when connected.
Also check USB 5V line.
USB flash drive sinks less current than an external SSD.
Probably get lower voltages than normal when mentioned devices are connected...

 

[cwalex]

With wifi card plugged in I get 3.3V and 5V. My SSD USB draws around 300mA at the highest I have seen on my USB meter and the voltage stays at 5V.

I just noticed that there is long screw damage on the heatsink screw for U1100. It's the one between the RAM and U1100. Considering the USB comes from U1100, there is a good chance that a trace got smooshed into the ground plane or something.

 

[2informaticos]

PCH practically controls all the preipherals.
Check resistance to ground on USB lines, on diode mode.

USB SSD issue present on USB 3.0 only?
Connect it using USB 2.0 adapter, or viceversa.

 

[cwalex]

0.64V on both P and N measured at L4600

I have been using the SSD with a USB2 cable.

 

[2informaticos]

And USB flash drive tested was 3.0?
Did you try both USB ports?

Check L4600 and U4650.
U4600 works properly?

 

[cwalex]

yeah it works on both ports with USB2 flash drives.

L4600 has continuity about 3.4 ohms. I'm assuming U4600 is working due to the 5V being present and the U4650 mux since it is working with my flash drives but do you think I should try changing those in case they are only partially functioning?

 

[2informaticos]

So USB 3.0 not working, but 2.0 is OK?

 

[cwalex]

I ran the USB device presence test in ASD for USB2 and USB3 devices (flash drives) and it passed. It won't boot from my USB2 2.5" SSD however.