How to clean up lab after big capacitor blew?

[GeekGirl]

I used to connect 50V 1000uF electro's to mains cables, bury the electro ~ 200mm in the ground and then plug into the mains They made great little land mines Lovely loud bangs and dirt flung up to 4m in the air I tried a really big one once (I can not remember the ratings but it was bigger than a can of coke), it sat for a bit humming then made a fair hole in the ground, a fair few neighbors came out to see what the bang was

[Old Printer]

Had a 5000 watt metal halide uv exposure tube blow once. It took out the 3/8" thick tempered glass safety plate which took out the 4x4 foot glass faced exposure frame under full vaccume. No real injuries, but between the flying glass and the noise it was a real brown streak shorts changer. Hell of a mess to clean up.
Is that electrolyte sodium based? That's what the residue looks like.

[SeanB]

Electrolyte is probably borax based. Kind of popular base for electrolytics, though the actual blend is a real witches brew.

[jtu]

Is that electrolyte sodium based? That's what the residue looks like.

How to tell? Feels very much like paraffin wax.

[jtu]

I think I know what caused the blow. I think it is "Boys and girls, don't use cheap caps from noname" story.

As I wrote above I use chap capacitors for experimenting, "breadboarding" so to speak. You can't forecast everything anyway during that, I am thinking.

Recently I got new LCR meter, DER EE DE-5000. Naturally, I went to measure everything within reach

When I measured 8 remaining caps from the batch, I got that 2 seem to be fine, ~8500uF, but remaining six a few pF - few nF max.

So, it is "Measure your caps if you use noname, boys and girls" story probably.

[GerryBags]

It's the smell that gets me. Once it gets up my nose it seems to linger for weeks! I attempted to desolder some SMD caps, and all it did was make them pop. Luckily there's not much in them. i'm so glad I didn't pop one of your 8500uF jobbies! I'd have to relocate.

[jtu]

In my case the smell was not the worst, cleaning was

[dmills]

See you the cap smell and raise you a Selenium Rectifier....
No other smell quite like it.

Regards, Dan.

[Mr. Scram]

Don't use a plexiglass box. That will shatter in a worst case scenario. Use something like lexan instead. That will bend, scratch and deform easier but is a lot less likely to shatter.

[james_s]

See you the cap smell and raise you a Selenium Rectifier....
No other smell quite like it.

Regards, Dan.

I had a selenium rectifier burn up in an old power supply my uncle had that I plugged in when I was probably 8 years old. That stench is still burned into my nostrils to this day, blech! Seems like the smoke it put out was green but that could be my imagination.

[tron9000]

I think I know what caused the blow. I think it is "Boys and girls, don't use cheap caps from noname" story.

As I wrote above I use chap capacitors for experimenting, "breadboarding" so to speak. You can't forecast everything anyway during that, I am thinking.

Recently I got new LCR meter, DER EE DE-5000. Naturally, I went to measure everything within reach

When I measured 8 remaining caps from the batch, I got that 2 seem to be fine, ~8500uF, but remaining six a few pF - few nF max.

So, it is "Measure your caps if you use noname, boys and girls" story probably.

There is another situation where blown caps can happen.

A while back I took a TTi power supply out of storage, it had been stored on its side, carelessly packed.

plugged it in and the large caps inside had all blown.

It had been stored for quite a while and we came to the conclusion that the electrolyte may have settled to one side.

[Doctorandus_P]

> Compressed air and compressor are good tools.
>  Especially for blowing out moisture left from water or any other liquids.

No, no, no.
Do not do that.

The stuff you can see is relatively harmless.
But what you do with a compressor is blow the liquids into slits and cracs between buttons, into potentiometers and into everyting else.
And that is the last place where you want to have liquids.

All the bottons of your Siglent are probably a continuous piece of silicone. If you notice after a month or so that the bottons are sticky, then you can completely dismantle the front panel of your scope and wash it with water & soap.
If you have such big parts without slots in them, then you can use an compressor to blow them dry.
But if you use the compressor on your oscilloscope, you will also blow the liquids into the encoders and between the front panel and the buttons.

Also:
The most common cause for exploding elco's is reversing the polarity on them.
They will start leaking current internally, and the curren breaks down the thin insulation (oxide) layer.
The power dissipation heats them up untill the electrolyte boils and then you have a pressure vat.

"old" elco's which have not seen a significant voltage for a long time may also get leaky.
These can be "re generated" by slowly inceasing the voltage ( with the right polarity) over it.

[GerryBags]

Don't use a plexiglass box. That will shatter in a worst case scenario. Use something like lexan instead. That will bend, scratch and deform easier but is a lot less likely to shatter.

Quite right! The old WW2 bombers with the ventral MG turrets used Lexan for the canopy so that a bullet would make a hole and pass through without shattering the canopy. The safety shields designed for lab use can point you in the direction of usable designs (https://www.coleparmer.co.uk/c/safety-shields?gclid=Cj0KCQjwuYTYBRDsARIsAJnrUXDUEQTUZ3Fb2qbu5k6tKUa5Lxk9h6TiWc-M-P1cI462NDXsAv9qfV4aAg_jEALw_wcB) but you could obviously obtain the materials and make something for much less money. a metal plate with a slot cut into it and an electric bar heater underneath can be handy for making bends.... one of the only useful things I learned in three years of CDT courses at school.

[jtu]

> Compressed air and compressor are good tools.
>  Especially for blowing out moisture left from water or any other liquids.

All the bottons of your Siglent are probably a continuous piece of silicone. If you notice after a month or so that the bottons are sticky, then you can completely dismantle the front panel of your scope and wash it with water & soap.

Buttons are fine.

The most common cause for exploding elco's is reversing the polarity on them.

Was not my case.