TU56/TC11 restoration - Power supply question

[Pete Turnbull]

On Mar 16 2005, 17:53, der Mouse wrote:

> Well, I've never had a cap in a power supply go bang.  But I did once
> put together a circuit and carelessly use a cap rated for about half
> the expected voltage - I was checking only the capacitance, my bad.

I've had two electrolytics fail spectacularly.

The first was one that had just aged.  It was a large PSU electrolytic
in a valve[1] PA amplifier.  I'd had the amp running several times, for
an hour or so at a time, but on one occasion, it just blew.  It made a
loud hissing noise, and ejected a stream of white fumes.

The second was a non-polarised electrolytic in an Atari monitor.  The
original had failed, so I looked through the catalogues for a similar
type.  The only one I found of the same capacitance and voltage claimed
to have a suitably large ripple current capacity, but was quite a lot
smaller than the original.  I was a bit skeptical, but hey, technology
moves on and capacitors get smaller every year, right?  It lasted about
90 seconds.  The bang was spectacular, and the amount of fibrous
padding that came out of such a small space was really impressive.  The
ceiling still has the dent in it, but the monitor now has a
polypropylene cap instead.

[1] British for "vacuum tube"

-- 
Pete						Peter Turnbull
						Network Manager
						University of York