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Subject: [DPRG] USB
From: DeltaGraph at aol.com DeltaGraph at aol.com
Date: Wed Apr 5 04:02:58 CDT 2006


If you have trouble finding info for your motherboard:

I got interested in my suggestion to determine which is 5V and which is 
ground then guess on the data lines -- and reverse them if interface does not work.

I seem to remember doing this on a motherboard back in the days when USB was 
very new.

(Maybe someone could scan this post and comment on soundness of my approach)

This link might give more information and seems to confirm my approach.


My guess would be safest to use a volt meter rather than an ohm meter to 
determine which is 5V and which is ground -- although I would be surprised if an 
ohm meter could damage a USB driver/receiver.

My suggestion:
Connect the common of the volt meter to a known ground (say from a disk drive 
connector) then probe the lines on the connector. 

Of course a scope might even be more helpful, but not sure if needed. I can't 
tell you off hand what is happening (datawise) on an empty USB bus 


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