1. Home
  2. Electronic Components
  3. Can you tell if a capacitor leaked by dissecting, and looking at the brown paper?

Can you tell if a capacitor leaked by dissecting, and looking at the brown paper?

Originally posted in Sci.Electronics.Repair, but everyone wants to dance around my question. Does anyone here have the answer?

Can you tell if a capacitor has leaked by dissecting it?

My JVC stereo is humming loudly. There are signs of an obvious capacitor leak around three large capacitors on the board. Brown crust.

I replaced two large 6800uf 40v caps, but the humming remains. So I pulled the third cap, a smaller 3300uf 35v unit.

For fun, I dissected all three.

Each large 6800uf cap had dark brown paper all the way through. Viewed from the top, the spiral of paper was consistent in color.

But the smaller 3300uf unit, when the paper spiral was viewed from above, the center of the spiral was a lighter color than the rest of the paper.

Does this mean I have found the leaky unit?

I have no way to test them.

PS

1) I am QUITE sure it wasn't glue used to hold down the capacitors.

2) I know the electrolyte is acidic, okay?

3) I know all about Usenet, and that I can't control responses of others. But please, please try and answer my question?
Reply to
bryanska
Loading thread data ...

Added some pics on Flicker.

Doesn't it seem odd, that the cap's fluid is so poorly distributed?

formatting link

Reply to
bryanska

No. You can tell by the leak though !

Graham

Reply to
Eeyore

The paper should be light in color and damp. It should have an ammonia-like odor to it. If it feels dry, yes the electrolyte leaked out. Most electrolytics have a vent in the seal at the terminal end. Over time they tend to dry out. As ambient temperature and atmospheric pressure change, the liquid is "pumped out" as vapor. They dry out even faster if they are passing too much AC current.

Al

Reply to
Al

If you dissect it, you have to replace it anyways. Not very constructive.

Suggest you weigh the parts and compare to others known-good.

If in doubt, replace anyways.

Drying out is the expected end of life of an electrolytic, which may have a design life as low as 200hours at it's maximum ratings.

Consumer equipment is not normally expected to be operated under worst case conditions - units that are will age sooner.

Sometimes equipment may be accidentally plugged into an inappropriate source, or left to run for long periods, unattended, in fault-like load conditions ie into shorts, on top of heaters, under a deluge of soap suds, etc etc.

How old was the unit?

RL

Reply to
legg

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.