"Charles Wm. Edwards" wrote in
message ...

I was listening to the unit one night when all of a sudden the sound cut
out. The front panel LEDs still work. After opening the unit I found all
four line in fuses blown. (2) 4 amp and (5) amp fuses. Bought new fuses
and installed thinking a surge in the incoming house power could have
been the cause. As soon as I turned the unit on the new fuses instantly
blew. Can anyone give me an idea as to what could be happening. Thanks.




--
Charles Wm. Edwards

Depends on how the fuses are blowing. If they are failing hard, with a
bright flash and the fuse wire totally vapourised, then the problem is close
by - possibly something like a failed bridge. If the fuses blow soft, with a
gentle flash, and the centre of the wire just melted away, then the problem
is well downstream of the PSU - probably one or more short circuit output
transistors. Unless you have experience of working on this sort of kit, you
are unlikely to get to the bottom of the problem. Although shorted output
transistors are easy enough to find, this is seldom the end of the story
with DC coupled amps. You may spend quite a bit of money on replacement
transistors, only to have them just fail again, as soon as you switch on.
Don't believe for one minute that the fuses are there to protect the output
transistors ...

Just as an aside, I assume that you are replacing the fuses with like for
like typing for the originals ? Most amplifier fuses are "T" rated types. If
you use "F"s, they likely will blow as soon as you switch on, even with no
fault present.

Arfa