I am always cautious when thining about an amp that has no fuses and more so when they don't have the cap. Experiance has taught me that usually something is fried in it and it is not "Just needs a fuse..."
Sounds like you blew the fuse trying it on the new amp but the light went on on the Lead so.....that's a strange one. I have had fuses look fine and be blown as well as fuses that test OK but blow as soon as they are put back in a working amp. I figure it almost blew in the first amp, then did in the second. As commented on several times in this forum; always make a matrix when checking out amps. One never knows if a cord or cable might have gone bad during testing (it can happen) and you sometimes end up chasing a rabbit down a hole when you just needed to change the cable. Check each component one at a time, never, never change two things at once. Always check the component on a working amp or speaker before moving on. My guess, from out of the blue is a bad power supply....keep us posted willya, huh?
