I have a very cheap amp in my car, 300w and its worked for ever.
Recently for no apparent reason its stopped working, however....
The power LED still comes on with the stereo, the audio leads are good, all connections to battery, ground etc are good and all fuzes are ok?
I have also now changed the HU for a Sony one to see if that fixed it but nope, stil nothing.
One thing I have noticed is, previousley if the amp was on and I accidentally touched the phono lead to the case of the amp it would cut in the safetry overload feature (red led instead of green) but that does not seem to hapen now.
Any experts out their know where I could start looking, or is the amp busted?
I'm affraid to say it's probably buggered.
If you are certain all the wiring is ok and the fuses are fine there's not alot else it could be. You could run over the wiring with a tester as a double check just to make sure there are no breaks in the wiring you haven't spotted. Obviously make sure the live feed from the battery is ok and also check there is power in the remote wire from the HU when the HU is switched on.
I had a similar problem with my amp, turned out to be a blown fuse on the main feed from the battery. The fuse itself looked ok (could still see the wire intact through the glass) but when tested proved to be duff, I still had the power led on the amp light up due to the supply from the remote wire, but no main feed meant no power. This one is always worth a try.
Other than that somthing internal on the amp has gone. My best mate had his Alpine mono block just stop for no reason. All wiring checked out fine, when another amp was connected in its place worked fine too (if you can get your hands on a friends amp could try this too).
EDIT: Sorry just missed your reply to Don, try option 1 then, prob your safest bet!
Ended up sending the amp off for repair, can't remember which component had blown inside the amp, but was fixed to the tune of £80. Still not bad for an amp costing £250. Turned out it had blown due to a bit of damp in the boot. Have you got any moisture, how ever little in the boot?
Let us know how you get on.