[SunRescue] exploding sun psus

[Christopher Byrne]

Yep, I'm sure, it was a 5 farad cap, at least that's what the diagram said.
It was an early solid state system with a 500 watt continuous amplifier.

Serious audiophiles regularly install networks of capicitors with a total
rating of well over 10 farads, and single capacitors of up to 120 farads are
available on the open market. Also large scale power transformers use HUGE
capacitors (kilofarads) to regulate line levels.

I didn't know that it was a 5 farad until it blew up (literally the thing
exploded) and I looked at the circuit diagram from the guy who built it. It
was custom built for an open air church in Northern Arizona, and I happened
across it because I was an amateur radio operator, and some of my friends
were members of the church, who just happened to know I was into electronics
etc...

Anyway they said that it was having trouble and asked if I could look at it.
So the fired it up, and we went to the mike to have a test, my friend
talked, it crackled for a bit then BOOM, the damned thing toasts itself. I
can believe it was five Farad because the thing was so large(about the size
of a quaker oats cannister according to the circuit diagram).


Chris Byrne

-----Original Message-----
From: rescue-admin at sunhelp.org [mailto:rescue-admin at sunhelp.org]On
Behalf Of Scott Newell
Sent: Thursday, December 07, 2000 11:15
To: rescue at sunhelp.org
Subject: RE: [SunRescue] exploding sun psus


>Man I have been there. Anybody ever seen what happens when a 5 farad
>capacitor blows? No five pico-farad or micro-farad, 5 farad. It's pretty
>damned impressive. That was in a very large, very old public address
system,
>and the smell and mess were pretty awful lemme tell ya.

5 farads (!).  Are you sure?  I've seen caps (supercaps?) intended for
non-volatile memory backup at 1F or so, but they're all rated at 5V or less
and have enough internal impedance to make the maximum pulse current output
pretty anemic.

I've also seen some reports in the trade mags about recent progress in
multi-farad sized caps double layer 'ltyics (Maxwell ultracaps?) with great
output pulse ability, but again, only at low voltages.

Seems to me any very large, very old, PA system would be running vacuum
tubes, and the power supply filter caps would each be in the 100s to low
1000s of microfarads.  Significant energy storage to be sure, but I just
have a really hard time believing an old PA system had a 5F cap in it.


newell

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