Question Electric shock from 3.5 mm input jack of speaker!

[Dadrian Daedalus]

I recently bought a 4.1 speaker system for my pc. The speakers in question is sony sa d40.

However after setting it up, when i attempted to connect it to my computer via its 3.5 mm aux cable, i got a mild shock on touching the tip of the 3.5mm jack(the other end of it was connected to the speaker itself).

This seemed a little odd-i tested the jack with a current detector and it lit up, thereby confirming my suspicions.

As reference, i compared it by testing the 3.5 mm inputs of an old creative 5.1 system that i also have, but could not detect any traces of current on them.

Is my new Sony speaker defective? Could using it possibly damage my pc? Why is it outputting a small amount of current via its 3.5 mm aux input cable?

 

[Ralston18]

There is an electrical short somewhere within the speaker system.

And I trust that you did not, and will not, connect that 3.5mm jack to your computer.

The problem could become worse and send even more current through you and/or your computer. Likely to end badly one way or another.

Return the system and get a replacement that does not shock you.

 

[Dadrian Daedalus]

The shock wasn't very severe, it was in fact more like a tingling sensation.

One curious thing i observed is that my speaker which is connected to my ups, only gives out some current via its 3.5 mm aux input cable when the ups is running via ac mains, but the current disappears when the ups switches to battery.

If there's a short in the speaker, wouldn't it output the current under all circumstances, irrespective of what its power source is?

 

[Ralston18]

Not necessarily.

You can receive an electrical shock via a device that is powered off. (Hence many devices come with warnings to unplug before servicing.)

All it takes is a problem, a wiring error, or some other situation that allows current to flow where it should not normally go.

For example, in your situation, the UPS likely has a problem that is allowing AC to flow into the speakers via the ground/earth.

Or perhaps the wall outlet serving the UPS is the source. [And there should not be any interim power strips or surge protectors between wall outlet and UPS.]

When AC is off that source of electrical energy is gone. And the electrical energy provided by the UPS battery takes a different path and does not feed into the speakers.

Take a close look at the 3.5 mm audio plug. Most likely to be TRS or TRRS. Which means that the current you feel could be routing through the sub-woofer, one or both speakers, or ground.

Overall, if you have a multi-meter and know how to use it (or know someone who does) you may be able to troubleshoot and narrow down the problem source.