What does this SMD component do?

[ckuethe]

I seem to have knocked a small SMD component off my Zero (v1.51) near the USB ports - based on the v1.4 SMD layout it’s “FB1”, a common mode choke for the USB3?

So far everything the important bits are working, wifi and a USB3 SSD:

root@rdx0-3:~# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/4p, 5000M
        |__ Port 1: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/2p, 480M
root@rdx0-3:~# dd if=/dev/sda bs=4096k | pv > /dev/null
13.9GiB 0:01:09 [ 205MiB/s] [                             <=>                  ]

Is this actually a necessary component?

[theophile]

It’s basically a HF filter for the high speed data lines. You might be able to get by without it if you’re just using USB2 speeds, or if your operating environment doesn’t have much EMI/noise. Otherwise you might have flaky USB3 connections or speed losses.

[ckuethe]

Thanks. I don’t know enough about how USB3 really works, electrically, but it seems to me that USB shouldn’t work at all if this filter is missing since I now have an air gap between 1-2 and 3-4.

A USB2 device I just plugged into the hub doesn’t work, so maybe it is necessary. I guess I’ll try bridging it with wire or just use this for non-usb applications now.

[theophile]

You’re correct. I assumed from your original post that you had bridged the pads already because it sounded like you were saying a USB hard drive was working properly. The best thing to do would be to order a new choke to replace the damaged one.

[ckuethe]

I’m not really set up for fine pitch soldering; under a magnification it appears that the pads have been ripped off. I’m thinking its next life will be as some sort of micro-NAS, travel movie server, or massively overpowered airstash.