Turned out to be a problem with the speaker. Push the speaker cone in and it works, leave it as it should be and it does not. Changed it for a spare Sony 10" one and its working again, sounds better with the old paper cone as well, rather than the plastic one
Very weird as I have never had this type of problem before, still, its all fixed now.
Troubleshooting steps in order as follows.
1. Check amp fuse, and main fuse at battery
2. Check all wires, change phono leads etc
3. Ensure there is not a problem with output from head unit (tried an alternative HU)
4. Try another Amp
5. Check connections at speaker (I also pushed cone in and it came on)
Removed old speaker from box, put new one in and its all up and running
Ah bugger, should've thought of that one!! Happened to me too! Never mind
I was thinking amp trouble
Happened to my JBL sub, turned out to be the 2 wires going directly into the cone that broke, some how they had an internal break in them, a little wiggle would get it working, or if you pushed the cone to mike them tight. Decided to solder them up, but just kept going again a bit futher up. They must breakdown after a few years
I've seen some of the
at the base of the cone burn too, so they only work if it's pushed in or out slightly.
At least you got it sorted now