How to tell whether this capacitor is working?

[wwenze]

Blast cheapo local-brand LCD TVs, this one decided to give problems right after its 1-year warranty.

Already spotted one TEAPO cap waiting to burst. TEAPO, eeeewww.

How do I see whether this kind of capacitor is still working? Pic below.

[Mooly]

ANSWER, BUT DON'T TRY THIS... you use a 'scope and examine the ripple component... but as that looks like a mains reservoir cap on the primary side of PSU DON'T.
You need a fully ground isolated workshop and test gear to do that.

So you either swap it, or put another in parallel to prove.
Also if it's used as I describe, depending on your mains voltage see if the DC volts is correct... 240vac mains gives 350 or so when rectified and smoothed... it's not a reliable test however.

The cap may well be OC... it's a reasonably common fauly generally.

[Frank Berry]

TEAPO caps are among the worse. I'd replace it. Don't even bother to test it.

[wwenze]

I was hoping to find an answer along the line of visual or physical confirmation, like being bloated for the non high-voltage caps. I heard the top is supposed to pop off? But haven't seen one before.

BTW is the brand suscon ok?

[Mooly]

Originally Posted by wwenze

I was hoping to find an answer along the line of visual or physical confirmation, like being bloated for the non high-voltage caps. I heard the top is supposed to pop off? But haven't seen one before.

BTW is the brand suscon ok?

Well google images show examples,
failed electrolytic capacitor - Google Images

Most failures of SMPS are down to caps... what normally happens is the ESR becomes high... the "value" remaing correct. It's a bit like adding a resisor in series with a battery... it always reads the correct terminal voltage but can't supply current. Same thing with the caps simply speaking. That's why normal capacitance metes are useless for testing.
Small values just as prone to failing... best policy is to do a "blanket" change and replace all with suitable 105 degree low ESR types.

[wwenze]

Well call me scrooge, but I don't have that value on-hand and it costs $10 to $20 for the good ones where I live. And I need the TV back up working ASAP, like, today. Since it belongs to my mom and dad rather than me.

The TV is working but the symptom of failing reservoir caps - unable to start right after switch on - is appearing at an infancy stage so I'm striking first before I go back for my studies after the new year. Probably that's why I only see one bloated TEAPO and no leaking out of the 7; I've seen PSUs and mainboards in worse conditions that are working.

In short I can't and I won't be changing that capacitor and saving it for Easter, but I just want a peace of mind that it is still working. Merry Christmas and a happy New Year.

But that cap also being a TEAPO is not so peaceful on the mind.

[Tony]

electrolytic caps are expendables, replace them at the slightest hint of trouble, you will be glad you did...

[Mooly]

Originally Posted by Tony

electrolytic caps are expendables, replace them at the slightest hint of trouble, you will be glad you did...

Exactly
Having worked on 1000's of failed PSU's in TV's VCR's etc etc I know the problems caps cause.
I wouldn't bet on your fault being the reservoir cap... it may be, but is also just as likely to be a small cap too.
And failure of some of those cause catastrophic failure of the PSU... i.e a blow up with short circuit chopper and other damage.

[wwenze]

Never said the fault was that big one on the primary, already knew the problem lies with a bloated 1000uF 10V TEAPO. Replaced that one with a Panasonic M series 1000uF 16V and the TV is now good to go.

Didn't replace all after realising that the M series is rated for only 85 degrees while the original TEAPOs are 105. Though knowing how TEAPO caps fail in computer PSUs anyway despite being exposed to just 60+ degrees, well...

As said before any overhaul will have to wait until Easter. Probably go overkill with some Panasonic FC. Will my picture look better I wonder?

[dhaen]

Originally Posted by Mooly

Exactly
...
I wouldn't bet on your fault being the reservoir cap... it may be, but is also just as likely to be a small cap too.
.....

It's often the cap near a heatsink or a power resistor. Heat (internal or external to the cap) is the killer.