Lance:

Typically a PSU cap (Especially vintage FP types) will have a ticking or
spitting sound prior to failing when the capacitor plates short-out and the
electrolyte starts to ooze out of the bottom seal (Whitish_Brown Powder like
stuff).

If you had a whooshing sound and actually had a Tube Fail you must suspect
something like a shorting signal capacitor, a bias problem or a crispy
resistor that shorted out vs.opening-up. Also a shorting wire could also
have caused this.

Open her up and with a good 100 Watt lamp spend about 1/2 hour looking at
the underside of the chassis for telltale signs of carbon deposits, visually
burned components or anything like a shorted wire or funny smells.

Most often a failure that takes out the fuse has it's roots in a DC short
which caused the Power Transformer to exceed its ratings and take out the
fuse.

Thanks heavens for thiose 0.25cent fuses, they have saved many a precious
Mac Transformer.

Buena suerte amigo,

Rich Sherman

wrote in message
...

hi, i have a pair of old mac 50-w2 mono blocks and one got sick tonight.

the first symptom was a rushing noise a few seconds after the amp was
turned on, much like being between channels with a old tube AM radio.

i powered it off and suspecting a tube swapped tubes with the working amp.

problem satyed with the same amp - so not likely a tube.

i then swapped outputs to the speakers - problem stayed with the amp -
so not the speaker.

when i put it all back together and tried again, one of the output
tubes flashed blue and the fuse blew.

when i've had similar problems in the past, it's been a bad tube,
but it doesn't look like that this time.

thoughts?
--
Lance