The_Handy_Andy
Posts: 37
Joined: Sun Jan 17, 2016 7:13 pm

USB hub mod

Tue Apr 19, 2016 3:56 pm

Hi hoping for a bit of help. The first image is of the PCB of a hub I got cheap from Maplin (Unitek Y-2142) where:
A. Power in (pin is +)
B. Is the host conection
C. are USB ports
D. Is a 2A (max) iPod charging port (no data connection)
hub02.jpg
hub02.jpg (53.14 KiB) Viewed 1339 times
What I am thinking of doing to remove the risk of backfeed (which may be a good/bad thing), is to cut the track at point 1 and solder a diode between points 2 and 3.
hub01.jpg
hub01.jpg (41.26 KiB) Viewed 1339 times
The questions I have are:

1. Is this a good idea / will it work?
2. What diode should I use?

Thanks
Andrew

The_Handy_Andy
Posts: 37
Joined: Sun Jan 17, 2016 7:13 pm

Re: USB hub mod

Tue Apr 19, 2016 3:57 pm

PS the images have come out in the wrong order (doh!)

gregeric
Posts: 1509
Joined: Mon Nov 28, 2011 10:08 am

Re: USB hub mod

Tue Apr 19, 2016 4:13 pm

With what model Pi will you use the hub?

If Zero, use it unmodified & allow it to backpower - just don't connect any other power supplies. Similarly with the A+, though be aware you'd be bypassing the main 2A polyfuse protection.

Other Pi with 40-pin header: just cut the track & don't bother with a diode. A Schottky diode can be fitted if you insist / want to use it as an unpowered hub as an occasional option.

The_Handy_Andy
Posts: 37
Joined: Sun Jan 17, 2016 7:13 pm

Re: USB hub mod

Tue Apr 19, 2016 6:06 pm

Iv'e got 2 Pi2s.

gregeric
Posts: 1509
Joined: Mon Nov 28, 2011 10:08 am

Re: USB hub mod

Tue Apr 19, 2016 6:20 pm

Cut the track in that case. Diode (anode Pi side, cathode hub side) optional, only of use should you remove the hub's own power cable.

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