Noisy serial port

[farbs]

Well the title kind of says it all.
When I plug the serial cable from computer to amp I am am getting noise out of speakers. A kind of low hum:confused: . It is a Rotel 1056. Any suggestions. It is just a 2 port serial card.

[danward79]

How is your serial lead connected? does it have a shield?

Might be worth disconnecting it if it does. Check your amp & pc is earth right too.

[farbs]

Thanks fo reply.
Bothe Amp and computer are both earthed correctly.
What do you mean by sheild. The com cable that I am using is actually the one that withe the amp.
The serial card is a pci serial board with two com prts on it. plugged directly into motherboard.
It works fine just a bit noisy and seem to figure out why.
The serial cable is sheilded