A subwoofer works usually as a mono channel device, which boosts the chosen bass freq's only. If the mains power is indicated as being present by a coloured light, ie., the power light goes out when the power cord is removed, then if you are confident in going inside the unit, with the power disconnected, you need the use of your senses to sniff/observe for damage, ie., burnt resistors, cables; sniffing can sense heated items, transformers, now use your fingers with thin cotton gloves (to avoid burnt digits) to locate hot components. If all is cold, then go further without your gloves to fine-tune your fingers. If no clues look for dropped equipment damage. Any printed circuit board cracks in the unit could be the answer. You now need past experience in the job to go further, this entails a new board or pay out for a replacement sub-woofer. Now is the time to re-think why you wanted a s/woofer in the first place. Perhaps the source equipment isn't placed on a proper hi-fi isolation table which I could tell them about. Speaker cable should be as expensive as you can afford, with gold plugs on them.
Clean your mains plugs and fuses often. I could go on and on. Contact Richard on my phone number 01823-663743.
Richard Tory, March 2007
