Bubbly ol capacitor - opinions?

[McKenna32]

I have a bubble on my capacitor! Only under the label though, the metal can looks normal shaped... I've had caps fail before but it's normally way more obvious.

What do you think? Is she dead? It's from a Grundfos Alpha2 CH pump that's refusing to pump...

 

[flameport]

It's destroyed. Replace before it leaks and destroys something else.

 

[Jurassicspark]

Looks like its time to replace it.

Check to see if its just not the skin of the capacitor peeling away?

 

[McKenna32]

It's definitely a bubble just under the wrap, it's not the metal body, I can prod it about with my fingernail

 

[Harry Bloomfield]

It's definitely a bubble just under the wrap, it's not the metal body, I can prod it about with my fingernail

It just looks like a minor manufacturing defect. It's the metal case, which swells when they fail, either the top domes, or the plug blows out from the base, leaking electrolyte.

Sometimes, their tops are deliberately marked with an indented triangle, to weaken them, so they can swell, none-catastrophically, and obviously.

 

[hllns]

Just replace it, it costs pennies and you've nothing to lose if it currently doesn't work

 

[McKenna32]

Just replace it, it costs pennies and you've nothing to lose if it currently doesn't work

Except I don't have that spec cap to-hand (despite saving every scrap power board that's passed my shed for a decade!) and ideally need hot water back tonight, so don't want to waste time buggering around with a cap that's fine and you lot might be able to tell me to go fish just by the look of it...

Through sheer coincidence with family I've managed to get hold of an old version of the same pump that's got me back up and running so it's not a pressing issue any more. I'll pop it off and test it on an LCR meter at work as I'm curious

 

[FrodoOne]

4.7uF 400V capacitors are readily available.

 

[RandomGrinch]

4.7uF 400V capacitors are readily available.

That looks like 47uF to me

 

[Ragnar_AT]

That looks like 47uF to me

Also an extremely common value, especially in switching mode power supplies.