Vented Capacitor

[Spiff4565]

I have a Voodoo Labs Pedal Power 2 that started humming when I first apply power to it. Pulled the cover and saw on cap bulging on top. Pulled the board and removed the suspect capacitor and sure enough, it's physically leaking on the bottom.





The fix is pretty straight forward at this point, however the capacitor has Vent on the labeling.

I can not find a vented cap with Mouser. Can I replace this capacitor with a non-vented style?

There are a total of 8 of these caps on the board and I'm half tempted to just replace them all while I in there. Also since I have to order it I may as well get my money's worth.

The cap value 1000uf 25V.

 

[benny_profane]

I can not find a vented cap with Mouser. Can I replace this capacitor with a non-vented style?

Unless this is something I’m not aware of, all new production, higher-capacity electrolytic caps should be “vented.” Take a look at any 10uF+ cap in your stock. It should look like it has a “+” scored into the top.

How old is the PSU?

 

[Spiff4565]

I'd say ten+ years

 

[jwin615]

Unless this is something I’m not aware of, all new production, higher-capacity electrolytic caps should be “vented.” Take a look at any 10uF+ cap in your stock. It should look like it has a “+” scored into the top.

The scores are designed weak points. So if it shorts, it blows up, directionally from the pcb(hopefully). At least that's my understanding.
@Spiff4565 I can't say I've seen vented caps that small in present day electronics. Only stuff pushing HV. Overrate the voltage and get a 130C rated cap if you can find one that will fit. Or consider a solid cap. I'd recap the whole thing though. If one failed, good chance others won't be far behind. A power supply in a little box is a lot harder life for caps than in a pedal.

 

[jwin615]

I'll add on, 130C rated caps are pretty much a must for any PSU that doesn't have a fan already. Rectifiers get hot. The heat plus thermal cycling wears on a cap. Also, those harsher conditions are what the rated hours are in reference too. A 16v cap can live happily in a pedal pulling ~100ma for a long time. It's a kush job. The PSU caps are out here digging ditches in the heat everyday. Terrible life to live. They either self immolate or you retire them early.
I'm sure some may not agree with some of this statement but I'm firmly in camp "overbuild everything when able and feasible"
Bad things can happen when power supplies blow. Best to do what we can on the front end.
</soapbox>

 

[jimilee]

I have a Voodoo Labs Pedal Power 2 that started humming when I first apply power to it. Pulled the cover and saw on cap bulging on top. Pulled the board and removed the suspect capacitor and sure enough, it's physically leaking on the bottom.

View attachment 75373
View attachment 75374


The fix is pretty straight forward at this point, however the capacitor has Vent on the labeling.

I can not find a vented cap with Mouser. Can I replace this capacitor with a non-vented style?

There are a total of 8 of these caps on the board and I'm half tempted to just replace them all while I in there. Also since I have to order it I may as well get my money's worth.

The cap value 1000uf 25V.

Did the power supply start humming or did the pedal, and what kind of hum was it. I’m suspecting (hoping) maybe I have a bad cap in one of mine. I can’t get rid of the hum.

 

[benny_profane]

The scores are designed weak points. So if it shorts, it blows up, directionally from the pcb(hopefully). At least that's my understanding.

Oh interesting. So the designated failure point is different than a “vent?”

 

[jwin615]

Oh interesting. So the designated failure point is different than a “vent?”

I e always thought of the vents and what you see on the bottom of large caps (rated 500vdc+)
Maybe they're both vents. But they are designed differently.

 

[Spiff4565]

I replaced all the caps I had replacements for. There are two banks of 10uf caps, each containing eight caps. For the bank associated with the DC power jack, I went with 25 volt and 105 degrees. The the other bank of eight I used 50 volt 105 degrees as that is what I had on hand. The temp rating is much higher on these replacements so should be good for awhile again.