not sure what you mean....
it's almost like it's 'overheating' something and then it won't work right...(that might not be the case, just how it appears to me)
When it fails or whatever it just puts out a steady 'pop........pop.......pop.......pop......pop'...(steady, like a drum beat, same tone too)
When I unplugged it yesterday and then put it back in it worked just fine while I was listening to the boob tube, and then in the middle of the night last night it starting doing it.
I've got to get a new fuse (it blew today when i put it in today.....the sub was humming first and then I unplugged and then when I plugged in there was no power).
It is a dahlquist QX10t model sub (part of the Orbit 5.1 micro home theatre series)....the sub is always powered but will put out sound when the receiver is kicked on. (is that what you mean by auto on)
The board looks ok (no apparent bad parts and such)....if I knew what to do I could probably fix it myself...
I don't feel like I abuse the speakers at all, sure sometimes I got the volume up but I have the bass setting on the subwoofer set in the middle and the receiver settings have the subwoofer 'normal'.
I found a link to the EXACT system I have....(just fix the http part)
hxxp://www.dahlquistcorporation.com/DQp9%20_Orbit_no_box.pdf