USB Port Switch Blown Up

[Sam Neall]

I have a four way USB port that just had one of the on/off switches smoke up. Could this be caused by the button being stuck, feedback from the device it was plugged into? For reference, the device I had it plugged into was an Arduino Uno R3. It was being powered off of the DC barrel Jack and was only using USB for signal. There’s another thing I noticed which was when I tried to plug the USB into my computer, the outer layer around the USB was sparking when coming in contact to my computer case. This is the only time this has happened. The port started to smoke as soon as I plugged the USB into my computer. The device was working yesterday and I haven’t changed anything.

https://files.engineering.com/getfi...dd-4750-4812-8358-8c55cd7284ae&file=image.jpg

 

[IRstuff]

Yowsa... Sparking, bad, particularly if it's from a "grounded" chassis connection. That says the grounds weren't actually grounds, or, at least, one them wasn't.

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[Sam Neall]

Update: all of the components that were plugged into the port died except for one. Not good...

 

[IRstuff]

With the damage shown in the photo, I would chuck the device altogether; trying to salvage functionality is pointless.

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[Sam Neall]

I’m not trying to fix it. I just want to know what the problem might be because I don’t want to get another one just to have it blown out again. If the problem was with the unit that’s fine, but if the problem could have been caused by a component that was plugged into it, that’s something I need to fix.

 

[3DDave]

It is probably a failure of the power supply. Cheap ones can put full mains power right to the output connection.

That is - the power supply to the Arduino board. Cheap power supplies can allow full mains voltage to the ground line. Check the barrel plug relative to the building ground; assume it is high voltage.

 

[itsmoked]

My guess...

The PC has a problem and is not grounded. When you plugged in the USB you grounded the PC thru what you plugged it into via the USB. This would explain why it zorched everything else too. If it was a typical DC over current kind of failure it should've only fried the board and the one USB device.

You should not physically touch any metal on your PC until you've gotten a DMM and measured from metal on it to a known AND proven ground connection coming from an unrelated outlet.

Do not disturb the PC or its power connections yet!
Use a grounded extension cord.
Plug it into a nearby but unused outlet.
Check its ground is good by measuring between it and the HOT from another outlet.
Once the extension cord ground is proven measure your PC case metal against it.
You can also measure from the ground to anything else associated with the disaster.




Keith Cress
kcress -

http://www.flaminsystems.com

 

[Sam Neall]

Ok so I found out that my room may/may not have ground. I read only 50v in between Ground and Hot on another outlet. have no clue why it was 50. I don’t really understand how The system that I have could be working for months before but all of a sudden went bad overnight. I was using it yesterday and it was working completely fine. Another thing that Would make sense to cause a problem that COULD change overnight if I accidentally bumped it or something after the last successful use is that the USB hub was in a box in close proximity to a 12 V power supply with 120V running into it. One of the USB extension cables that I had wired up could have had the exposed metal on it come to contact with one of those terminals. It wasn’t close to touching when I opened it though. Also, the USB extension cord that could have touched higher power wasn’t plugged into the port that blew up. That being said, I tried other USBs on my computer and I came to the conclusion that if more than two USBs are plugged in and the third USB is on a specific port where the paint is scratched off, it will make sparks regardless of what device is using it the deteriorated port. I know this is seriously unprofessional but it’s a home project so forgive my willful ignorance haha.

 

[Sam Neall]

Oh, and @3DDave The power supply doesn’t seem to be outputting anything as of right now. However I don’t think that rules out the possibility that it could’ve gone bad and sent 120 through the Arduino Before completely dying. I don’t think I need the power supply anyways so I will not be using it next time I put the machine together. The Arduino is doing very lightweight work. It’s just sending serial code at 11250 baud to a motor driver.