Originally Posted by RogerOH
If you had a multimeter you could check the circuit resistances to the rear speakers from the receiver end of the cables, but if you don't find any problems with connections at the speakers or at the receiver, it's pretty safe to assume the problem is in-wall."
im interested in testing the wires. anyone know how i can go about it?
i'll buy a multimeter if necessary, i'm just not sure how to use it. i want to test the signal strength going to the rear speakers.
Pretty easy for this, actually.
Get the multimeter and set it to the Ohms setting. This is the Greek Omega symbol (looks like a horseshoe).
Leave the test probes apart and see what the display looks like - probably will say something like "OL". Now touch the probes together and see what the display looks like - probably will show something like 0.2, give or take a little.
Now, with the speaker cables disconnected from the receiver, connect the test leads to the speaker cables at the receiver end of the cable(s)- one lead to each wire of the pair going to the left rear or right rear, etc. For an 8 ohm speaker, the DC resistance will probably be somewhere around 4 ohms, give or take an ohm or so lower to a couple ohms higher.
If you see a resistance that is 0-something, or way below 4 ohms, there is probably a fault in that circuit. Next, disconnect the speaker on the other end of that cable and make sure the disconnected ends of the cable are not touching. If the resistance measurement stays very low, there is a short in the cable somewhere. If the resistance goes back to that "OL" reading, the cable should be good to go and would tend to indicate a problem in the speaker.