Problem with Pioneer 850 receiver?
 

I can't seem to get any audio out of any of my speakers except the left-front one when I'm using stereo RCA plugs. When I use the toslink optical cable (for my dvd), I can hear audio out of the left and right front cables but not out of my center. Throughout all of this, I can't hear anything about of the back(left & right) speakers. What am I doing wrong? What setting should I be on to listen to 5.1 dvd's?

Here's some background info:

The receiver is an open box item. No manual, and the remote is not the one that usually comes with the receiver (it is the one that is sold with all the rest of the Pioneer models). Also the center and surroundback (left and right) speakers are all KLH ones which I got with the receiver for free. They're crappy but I know they work since I hooked 'em up to the frontleft&frontright hookups and they worked. So I'm thinking that there is something wrong with the settings of my receiver that is not allowing me to send signals to the center, rightback and leftback speakers. What should I change in the settings to be able to do this?

Also I'm using a passive subwoofer, and the manual says that I should use the backcenter channel to power the subwoofer and that I should change the settings to reflect this choice. I did the settings change but it is still not working, what should I do here?

Finally, the KLH speakers came with a really thin silver wire with black shielding. Could these be the problem?

Thx
Huzefa

i have the same receiver and being that its so simple to set up, i think yours is defective..stay away from open box and refurbs

You were right, I just forgot which input I had plugged the optical cable into. I been using it for a while now just testing everything out to make sure it's not defective and am pretty confident that it's not and that I got a great deal on it.