How do I troubleshoot my powered JBL Arc8 subwoofer. I have no sound at all from it. Is it the amp inside ?

Question

It has a green power light indicating it gets power. It is in excellent shape otherwise. When the rca plugs are removed from the receiver it is plugged into, the green light turns to red after a few minutes. I have also found that if i just plug in an rca jack to it, the light will turn from red to green (and stay on for several minutes)

Answer 1

It sounds like the input circuit is fine, but the output side may be blown or perhaps the internal wire to the speaker is damaged or the woofer cone itself is blown.

You will have to diagnose each one of these potentials by disassembly and analysis.   You need a 2nd speaker to test whether the subwoofer amp is working, and you can rule out wiring by visual inspection and the use of a multimeter, and finally rule out a blown subwoofer cone.

Answer 2

Two types of Sub-woofers, Self-powered (amp inside) or externally powered.

1) You said yours is internally powered. Connect the RCA to the Audio output of a DVD player, careful, you would have no volume control, just plug it and out. If it works, then your amp is faulty.

2) If externally powered, then try connecting it to another amp (if you have one) or you could try a battery, AA or AAA, as you tap in-and-out the battery into the woofer wires you will here a pop sound, if you don't then the woofer may be bad.

It's hard to give advise without knowing what you have, I don't want to feel responsible if something goes wrong.