Hi all,

Just a quick one. But first, I'd just like to reiterate that I'm
noting your comments on the ripple thread and will deal with them in
due course when i have a couple of hours to spare next Sunday.
Yesterday I had 2 minutes to waste so I blew up another electrolytic
capacitor - or rather I *tried* to. A 10uF 10V cap across the output
of a variac with Vo set to 240VAC. There was a considerable *pop* but
no bang and it turned out the T3.15 Amp fuse in the variac had blown
spectacularly - but the cap had survived unscathed! Tested fine for
capacitance and ESR! I never would have believed it. Just wondering
how the hell it didn't get destroyed...

CD.

Cursitor Doom <cd@notformail.com> wrote:

> Hi all,
>
> Just a quick one. But first, I'd just like to reiterate that I'm
> noting your comments on the ripple thread and will deal with them in
> due course when i have a couple of hours to spare next Sunday.
> Yesterday I had 2 minutes to waste so I blew up another electrolytic
> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
> of a variac with Vo set to 240VAC. There was a considerable *pop* but
> no bang and it turned out the T3.15 Amp fuse in the variac had blown
> spectacularly - but the cap had survived unscathed! Tested fine for
> capacitance and ESR! I never would have believed it. Just wondering
> how the hell it didn't get destroyed...

It's only doing it to annoy you. Make sure it is run well within its
ratings and put it on a board that has to be buried several layers deep
in some complicated equipment and is rivetted in place. It will fail
in no time at all and probably take several other valuable components
with it.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

On 2024/03/20 2:45 a.m., Liz Tuddenham wrote:
> Cursitor Doom <cd@notformail.com> wrote:
>
>> Hi all,
>>
>> Just a quick one. But first, I'd just like to reiterate that I'm
>> noting your comments on the ripple thread and will deal with them in
>> due course when i have a couple of hours to spare next Sunday.
>> Yesterday I had 2 minutes to waste so I blew up another electrolytic
>> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
>> of a variac with Vo set to 240VAC. There was a considerable *pop* but
>> no bang and it turned out the T3.15 Amp fuse in the variac had blown
>> spectacularly - but the cap had survived unscathed! Tested fine for
>> capacitance and ESR! I never would have believed it. Just wondering
>> how the hell it didn't get destroyed...
>
> It's only doing it to annoy you. Make sure it is run well within its
> ratings and put it on a board that has to be buried several layers deep
> in some complicated equipment and is rivetted in place. It will fail
> in no time at all and probably take several other valuable components
> with it.
>
>

Lots of parts can be forced way past their rated maximums and suffer
internal damage that won't then show for a period of time in normal use.

That's why we have fuses, TSVs, MOVs, etc to help protect against spikes
and their aftereffects.

The only way to find what happened to the cap is to take the capacitor
apart and study the elements under a microscope for punctures and do a
chemical analysis on the electrolyte.

This is just A-Waste-Of-Time experiment and I can't believe I am
commenting on it...

John :-#(#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
#7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

Cursitor Doom <cd@notformail.com> wrote:
> Yesterday I had 2 minutes to waste so I blew up another electrolytic
> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
> of a variac with Vo set to 240VAC. There was a considerable *pop*
> but no bang and it turned out the T3.15 Amp fuse in the variac had
> blown spectacularly - but the cap had survived unscathed! Tested
> fine for capacitance and ESR! I never would have believed it. Just
> wondering how the hell it didn't get destroyed...

Obviously it was able to survive the overcurrent situation for long
enough to blow the fuse in the variac. Since, as usual, you've left
off all useful information (i.e., make and model of cap) we can't
comment any further.

The fuse also did it's job, which is to protect downstream components
from overcurrent situations by blowing before the downstream items
themselves blow up.

In article <JaDKN.646227$xHn7.292649@fx14.iad>,
bertrand.sindri@yahoo.com says...
>
> The fuse also did it's job, which is to protect downstream components
> from overcurrent situations by blowing before the downstream items
> themselves blow up.
>
>
>
>

Fuses are really to protect the power source. They do usually protect
the wiring in the down stream device from a total meltdown.

On Wed, 20 Mar 2024 09:45:50 +0000, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

>Cursitor Doom <cd@notformail.com> wrote:
>
>> Hi all,
>>
>> Just a quick one. But first, I'd just like to reiterate that I'm
>> noting your comments on the ripple thread and will deal with them in
>> due course when i have a couple of hours to spare next Sunday.
>> Yesterday I had 2 minutes to waste so I blew up another electrolytic
>> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
>> of a variac with Vo set to 240VAC. There was a considerable *pop* but
>> no bang and it turned out the T3.15 Amp fuse in the variac had blown
>> spectacularly - but the cap had survived unscathed! Tested fine for
>> capacitance and ESR! I never would have believed it. Just wondering
>> how the hell it didn't get destroyed...
>
>It's only doing it to annoy you. Make sure it is run well within its
>ratings and put it on a board that has to be buried several layers deep
>in some complicated equipment and is rivetted in place. It will fail
>in no time at all and probably take several other valuable components
>with it.

LOL! Yeah, you got that 100% right I reckon, Liz. I realise I've
probably curtailed the service life of this cap by some considerable
amount, but nevertheless it's still remarkable it wasn't totally
destroyed. Vintage NOS parts for you: none of your Chinese rubbish.
:-)

On Wed, 20 Mar 2024 08:19:52 -0700, John Robertson <jrr@flippers.com>
wrote:

>On 2024/03/20 2:45 a.m., Liz Tuddenham wrote:
>> Cursitor Doom <cd@notformail.com> wrote:
>>
>>> Hi all,
>>>
>>> Just a quick one. But first, I'd just like to reiterate that I'm
>>> noting your comments on the ripple thread and will deal with them in
>>> due course when i have a couple of hours to spare next Sunday.
>>> Yesterday I had 2 minutes to waste so I blew up another electrolytic
>>> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
>>> of a variac with Vo set to 240VAC. There was a considerable *pop* but
>>> no bang and it turned out the T3.15 Amp fuse in the variac had blown
>>> spectacularly - but the cap had survived unscathed! Tested fine for
>>> capacitance and ESR! I never would have believed it. Just wondering
>>> how the hell it didn't get destroyed...
>>
>> It's only doing it to annoy you. Make sure it is run well within its
>> ratings and put it on a board that has to be buried several layers deep
>> in some complicated equipment and is rivetted in place. It will fail
>> in no time at all and probably take several other valuable components
>> with it.
>>
>>
>
>Lots of parts can be forced way past their rated maximums and suffer
>internal damage that won't then show for a period of time in normal use.
>
>That's why we have fuses, TSVs, MOVs, etc to help protect against spikes
>and their aftereffects.
>
>The only way to find what happened to the cap is to take the capacitor
>apart and study the elements under a microscope for punctures and do a
>chemical analysis on the electrolyte.
>
>This is just A-Waste-Of-Time experiment and I can't believe I am
>commenting on it...

Yeah, well you did. Incidentally, why are you Canadians so desperately
*dull*? It's like you have no sense of fun at all. You remind me of
that fellow Paul Carlson (Youtube, 'Mr. Carlson's Lab' is his
channel). Never seen him smile once in all the videos he's ever
released.

On 20/03/2024 15:22, Bertrand Sindri wrote:
> Cursitor Doom <cd@notformail.com> wrote:
>> Yesterday I had 2 minutes to waste so I blew up another electrolytic
>> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
>> of a variac with Vo set to 240VAC. There was a considerable *pop*
>> but no bang and it turned out the T3.15 Amp fuse in the variac had
>> blown spectacularly - but the cap had survived unscathed! Tested
>> fine for capacitance and ESR! I never would have believed it. Just
>> wondering how the hell it didn't get destroyed...
>
> Obviously it was able to survive the overcurrent situation for long
> enough to blow the fuse in the variac. Since, as usual, you've left
> off all useful information (i.e., make and model of cap) we can't
> comment any further.
>
> The fuse also did it's job, which is to protect downstream components
> from overcurrent situations by blowing before the downstream items
> themselves blow up.
>
>
More importantly the fuse protected the variac. They are
very intolerant of even quite modest overloads.
John

John R Walliker <jrwalliker@gmail.com> wrote:

> On 20/03/2024 15:22, Bertrand Sindri wrote:
> > Cursitor Doom <cd@notformail.com> wrote:
> >> Yesterday I had 2 minutes to waste so I blew up another electrolytic
> >> capacitor - or rather I *tried* to. A 10uF 10V cap across the output
> >> of a variac with Vo set to 240VAC. There was a considerable *pop*
> >> but no bang and it turned out the T3.15 Amp fuse in the variac had
> >> blown spectacularly - but the cap had survived unscathed! Tested
> >> fine for capacitance and ESR! I never would have believed it. Just
> >> wondering how the hell it didn't get destroyed...
> >
> > Obviously it was able to survive the overcurrent situation for long
> > enough to blow the fuse in the variac. Since, as usual, you've left
> > off all useful information (i.e., make and model of cap) we can't
> > comment any further.
> >
> > The fuse also did it's job, which is to protect downstream components
> > from overcurrent situations by blowing before the downstream items
> > themselves blow up.
> >
> >
> More importantly the fuse protected the variac. They are
> very intolerant of even quite modest overloads.

I have successfully protected one with a thermal cutout which has low
thermal inertia and has always operated before any damage can occur. It
is in a bench power supply that is often used to test faulty equipment,
so fuses would not give a quick and easy reset facility.

It suffered a lot of nuisance tripping on loads well below the variac's
rating until I realised that the isolation transformer, which it fed,
was drawing a large magnetising current. I have corrected the power
factor of the transformer with a capacitor and the nuisance tripping has
now ceased.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk