drain wires?

could someone tell me what drain wires are for?  i have never dealt with them before, and i think they may be causing me some problems.  2 out of my 3 preamp outs (at the amp end of the rca's) have no signal.  the 2 sets of cables with no signal have drain wires, which i dont know what to do with.  the third set does have a signal, and that set does not have drain wires.  so im wondering if the issue is with the drain wires, or if the preamp outs are just shot (i bought the deck used).  i know there are several easy ways to figure it out, but i just thought id ask before pulling the head unit back out.  thank you!

ryanoh, god... what did i do now??

Drain wires have nothing to do with the signal carrier part of the cable.  Drains are for shielding against RF and EMI interference.  If yu have no signal on the center pin of the RCA, then either the cable or the preamp is bad.

ok, thats what i was afraid of.  thanks for the tip.  by the way, are the drains supposed to be connected to anything, or just are they just supposed to hang there?  thanks again.

ryanoh, god... what did i do now??

Drain wires do exactly what they say-drain static electricity away from your signal wires.Ground one end only,isolate the other end. I`ve had very good results with them, grounding to the back of the head unit then running an extra ground wire from the back of the head unit to the chassis. This in addition to the internal ground wire on your wire harness.