Is my capacitor bloated?

GarzTeleMan

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My tech sent me this photo and told me that my capacitor is bloated. Can you please check this for me?
 

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Timbresmith1

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Just that one photo? I’m not seeing it unless the rubber seal on the bottom of the caps has swelled, causing them to lean at an angle.
The only other one I see might be one of the 2 that are hot-glued together. The left one might be a touch swollen if you look at the + on the aluminum on the top of it.
How old is the amp? Quality modern electrolytic caps will have a useful service life of 20 years in most guitar amp circuits.
 

Jon Snell

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Which electrolytic in particular?
They all look normal to me. C28 looks OK but is a non critical component and even if open circuit, will not affect the amplifier that much as there are further smoothing components in line.
Mind you, I have only been repairing and manufacturing valve equipment for 50 years, so what would I know.
 

Timbresmith1

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Just that one photo? I’m not seeing it unless the rubber seal on the bottom of the caps has swelled, causing them to lean at an angle.
The only other one I see might be one of the 2 that are hot-glued together. The left one might be a touch swollen if you look at the + on the aluminum on the top of it.
How old is the amp? Quality modern electrolytic caps will have a useful service life of 20 years in most guitar amp circuits.
If the one mentioned above IS swollen, I would replace all of the caps of that brand in the amp, if not ALL of the electrolytics.
 

Jon Snell

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Difficult to see a 3d component in 2d so we are all just guessing.
Normally when an electrolytic gets bloated, they lose capacitance and get leaky both electrically and physically.
There will be issues to accompany the 'bloated' capacitor like lots of 100HZ hum, 120HZ in places with 60HZ mains plus poor response to diferent frequencies.
 

hopdybob

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i would replace the "Black one on the left looks a little puffy .."
but what is to consider what amp it is and the price the tech will ask for the replacement.
 

clingin_on

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Nothing looks out of the ordinary to me.

The scoring on the tops of the caps permits the guts to spew out the top in event of catastrophic failure. And those tops aren't even bulging.

But your tech is the man on the spot.
 

jvin248

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.

+1 that black cap is putting out its belly like it had too many beers. It will still work for a bit but you'll have a problem soon that could take out other components.

Replace that cap and its twin right next to it at a minimum. Use a higher voltage cap than what is there so it can survive longer than these did. You should also inspect the other caps.

Remember that these can caps are not much more sophisticated than putting a strip of wax paper on aluminum foil and rolling it up into a cylinder to stuff in a little can.

Skip ahead to 2:20 min to see a capacitor winding machine at work.

.
 

Blackout Jazz

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The only thing I question is the left lead of the far left gray cap. Yellow stuff leaking? There is nothing wrong with the black caps.
 

Paul G.

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Photo is not definitive, but if (s)he sees it, I'd say ok. How old is the amp? If one electrolytic is going, they probably all need to go, unless the amp is new, then it's probably just a bad cap.

Electrolytic caps are a consumable, they do not last forever.
 

Jon Snell

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That yellow object is a sleeve for the resistor next to it.
The capacitors, if faulty/swollen, will produce odd noise/hum, and instability at low frequency. If you are not experiencing any of that, they are perfectly OK and unless you want to have them replaced for a 'just in case' moment, I would leave them where they are.
You will hear when they are in difficulty.

Why spend money when you don't need to.
 

KokoTele

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It's subtle, but that black one on the left clearly has a bit of a dome in the top where it should be totally flat. It's such a minor repair that I'm a bit surprised that the tech even asked.
 

Peegoo

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The two smaller caps are a teensy bit bulged if you look closely at their tops. The tops should be flat.

A clue is the fracture stamps in the end of the aluminum housing. These are die-stamped just like a pop-top beverage can, to break/fracture along a specific line.

When these caps become electrically 'leaky' internally (not necessarily oozing electrolyte), they overheat and expand. The fracture stamps allow the metal to crack and safely vent, rather than blowing the can off the soldered base like a bullet.

It's just a matter of time before they drift from spec and the amp will not sound as good as it should. Replace 'em.

You've got a very good tech.

Looky here:

Cap-Fracture-Stamps.jpg
 
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