USB fail after static discharge

[wuchy143]

All,

I"m working with a USB 1.1 keyboard which must go through a 7,000V static discharge directly onto it's DB-9 connector.(Chassis/Enclosure) Whenever this test is performed the keyboard has a couple failure modes.

1. Hit key after discharge and no output to computer. Though, any key struck after that has an output and is seen on my computer without a problem.

2. USB fails and must unplug the USB cable and plug it back into the keyboard. Once that is done it works fine. (Hard failure)

I"m a little lost as where to start with my debugging as I have never done any testing like this. Does anyone have some starting points which I could look into? Or are there some key things about USB which I need to look for?

Thanks for any responses!!!

-mike

 

[wuchy143]

so I figured out the problem on this. Basically chassis wasn't getting a solid connection from the USB connector. I made a pigtail shorting chassis directly to the shield on the USB wire and walaaa. No more failures no matter how hard I try. Now I just need to figure out a good re-work for production.