Question Speaker buzz when ANYTHING touches audio plug. How do I fix?

[Mugsy]

I upgraded my friend's PC. Everything was just fine before, but when I went to put everything back, his speakers now make a loud buzzing noise if ANYTHING touches the audio jack/plug... my finger, the computer... doesn't matter. The computer doesn't even have to be on. Simply touching the plug creates a "ground loop" hum.

It didn't do this before. And it clearly isn't a computer problem.

Does anyone know how to fix this? TIA

 

[CountMike]

That usually means bad ground/shield on input speaker cable.

 

[Mugsy]

That usually means bad ground/shield on input speaker cable.

Thx for the reply.

Is there anything I can do about that? I tried another cable and it didn't help.

It is a mystery why this started happening at the exact same time I replaced his computer. The problem is still there (buzzing if anything touches the audio plug) even though I brought his computer back to my place, so it has nothing to do with the new computer I just built, but he still blames me.) :/