→Testing speaker line
First, it is crucial to determine which model of audio drivers are being tested.
Then, disconnect the outside speakers from the two terminals on the back of the amplifier. Put a DC ohm meter across the leads going to the tower. If the reading is higher than the listed value, then one or more of the drivers could be open, or a connection is corroded. If lower, one or more drivers or the wiring may be shorted.
Determine the resistance of the Ohm meter's own leads by touching the two test leads together. Subtract the displayed value from measurements before comparing to those given below.
*Single functional PD60 driver will read 9.5 -
10ish ohms directly from the terminals on the driver, not including any wire*Four PD60 drivers will read 2. 5ish ohms when wired together in parallel with a short length of wire*Two PD60 drivers together will read 5ish ohms when wired together in parallel with a short length of wire*Four PD60 drivers wired into a speaker line roughly 250ft. in length will read 3. 8ish ohms*Four PD60 drivers wired into a speaker line that is 25ft. will read 2. 7ish ohms
# At the amplifier location, disconnect both wires of the speaker cable from the amplifier. Take preliminary measurement with speakers still connected on the two wires of the line at the amplifier end. Compare to the readings above (Testing Speakers) and write it down.
# Leave the two wires at the amplifier end disconnected, not touching each other, or any other conductive material.
# Go the speaker location, open the junction box, disconnect the cable from the amplifier from the speakers and take a measurement. There should be no resistance reading (no change on the Ohm Meter's display). Any numerical reading on the meter will indicate a short on the speaker cable.
# At the speaker location, short the two wires together on the cable that runs down to the amplifier. Then at the amplifier end of the cable put the Ohm Meter test leads on the two wires of the cable. A non-numeric reading will indicate an open (possibly cut) cable. For 14 AWG SJTO cable, you should see about 0.006 Ohms per foot of cable (don't forget to subtract the resistance of your meter's leads).