PSR-640 Line "HUM" Noise Via Mixer to Computer

I currently own a PSR-640 keyboard.

When I connect the "Aux Out L/R" to my the line connection on my mixer, and have headphones plugged in, I do not get any noise. When I then connect the "Stereo Out" to my computer's line-in for recording the output, a distinct HUM is heard. If I disconnect the 640's lines, the hum is gone, reconnect, and it's there again.

So, for some strange reason, when I have both the 640 and the "Stereo Out" connected to my computer's line in, I get a HUM noise. Funny thing is, I also own a DJX and I also have this plugged into the mixer, and I get none of this noise -- even with the Stereo Out connected!

I've tried also connecting the headphone out to the mixer, and same thing. I've tried plugged in the power supplies to the mixer and 640 to other separate jacks, but still no luck.

It's either the 640 or the computer that do not like each other. What's going on here? Why would the DJX not make noise and the 640 do?

Any help would be much appreciated!

Bryan Nicalek
ptshpboy@hotmail.com

Some instruments have noisey outputs that is discovered when you plug it into a mixer . But you could try turning up the 640 all the way , that will make it so you don't have to use as much of the mixers gain , that will eliminate some noise . It could also be bad cables .