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Bad capacitors : How to spot them

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+warwagon    10,031

Bad capacitors can happen on any motherboard, new or old. They can also explain issues that are other wise unexplainable.

1) Computer won't turn on

2) No display

3) Random bluescreens

4) Lockups

Just to name a few

When looking for bad capacitors on a motherboard, it helps to know what a healthy one looks like first.

A good capacitor usually looks indented, when viewing it from the top. In fact if you rub your finger over it you can feel the indentation

scaled.php?server=209&filename=38068174.jpg&res=landing

A bad capacitor or one that is starting to bulge will start to swell at the top, no longer looking indented

98164986.jpg

capblown_3.jpg

Others swell to the point of blowing thus you can see electrolyte brown crud on the top of the capacitors.

scaled.php?server=20&filename=swolleno.jpg&res=landing

Others Leak

capblown_10.jpg

In any case once you start to see the following symptoms it's time to either replace the motherboard, replace the computer, or know that the issue is not going away

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sc302    1,439

those would be blown capacitors. replace mobo or replace computer. it happens, usually due to heat/overheating, not enough to cause a thermal shutdown but enough to be above operating temp of the capacitors. is it common? yes, across lots of models and manufacturers. It is so common, that once pc's start acting crazy with blue screens and shut downs that the first thing I do is pop the cover off and inspect the motherboard.

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neufuse    2,823

if you have a newer motherboard with solid-cap's you won't find these signs generally... solid capacitor don't "bloat" like the older caps did

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+warwagon    10,031

Bare with me on the formatting of this thread. For some reason it wants to space out.

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CentralDogma    144

If you?re good with soldering, you can even replace blown capacitors.

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f0rk_b0mb    698

If you?re good with soldering, you can even replace blown capacitors.

Yup, that's what I'd do, however, it is not as easy as it looks. I had 2 years of electronics and my joints are never perfect.

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Rudy    457

My Samsung tv had bloated capacitors. At the end the tv would take 5-10 minutes to turn on (once on it was fine). I opened the TV and replaced the capacitors and it works great now

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Hell-In-A-Handbasket    277

OT

can see electrolyte

plant food in a computer ?

*edit - every time i see Electrolyte(s) i think of Plant food

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sagum    367

Yup, that's what I'd do, however, it is not as easy as it looks. I had 2 years of electronics and my joints are never perfect.

Through hole soldering is one of the easiest tasks to perform, can can be done with the most basic of kit. I've saved loads of motherboards, and monitors by replacing ALL the caps at once. They usually come in at the local electronics store at around ?10 for goodie bag full, certainly a lot cheaper then replacing a motherboard or PC... and certainly less wasteful then throwing out a otherwise perfectly good monitor screen and backlight.

I replace all caps if i find any that have died. usually if one is bloated or leaking, its a bad batch or the others are on their way out (or have already but just not showing visual signs yet). There is always an under line cause, mostly its cheap or dodgy batch of caps used when making the boards.

zocI3.jpg

I had some spare caps so I replaced just that one - it didn't work. So I replaced the rest, and even though they all looked fine, it fixed the problem.

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Crisp    3,271

Cannot I hit them with a hammer / screw driver to dent them again? lulz.

/s

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Mordkanin    225

Bad caps don't always bulge at the top.

An electrolytic will almost always bulge at the bottom first. You can tell if it's not resting flat on the board. (Source: I'm an EE. Also, I just ran a 10V 10uF cap at -15V for over a minute. Zero effect on the top of the cap.)

Be wary, when replacing capacitors. These days, organic polymer caps are coming into higher usage. They're used for higher ripple current applications and have generally better performance than the standard aluminum electrolytics.

If you replace one with an aluminum electrolytic, it'll probably overheat and fail very quickly, or lead to unstable operation from poor transient response, as they have an ESR an order of magnitude higher.

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+warwagon    10,031

Bad caps don't always bulge at the top.

An electrolytic will almost always bulge at the bottom first. You can tell if it's not resting flat on the board. (Source: I'm an EE. Also, I just ran a 10V 10uF cap at -15V for over a minute. Zero effect on the top of the cap.)

Can you post a photo of that. I'm looking but can't find one.

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ahhell    1,306

My Samsung tv had bloated capacitors. At the end the tv would take 5-10 minutes to turn on (once on it was fine). I opened the TV and replaced the capacitors and it works great now

Samsung lost a class action suit against them because of this. My DLP crapped out and I'm sure that this is the problem (that or bad solder connections).

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The Laughing Man    442

I remember the counterfeit cap issues from back in the day they were a huge cause of blow/leaky caps.

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f0rk_b0mb    698

Through hole soldering is one of the easiest tasks to perform, can can be done with the most basic of kit. I've saved loads of motherboards, and monitors by replacing ALL the caps at once. They usually come in at the local electronics store at around ?10 for goodie bag full, certainly a lot cheaper then replacing a motherboard or PC... and certainly less wasteful then throwing out a otherwise perfectly good monitor screen and backlight.

I replace all caps if i find any that have died. usually if one is bloated or leaking, its a bad batch or the others are on their way out (or have already but just not showing visual signs yet). There is always an under line cause, mostly its cheap or dodgy batch of caps used when making the boards.

I had some spare caps so I replaced just that one - it didn't work. So I replaced the rest, and even though they all looked fine, it fixed the problem.

Yes! Through hole soldering is the easiest. I really hate the ones where they rest ontop of the board. Like this. Just got done fixing this for a friend. Works! :)

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Hum    6,931

Ya think ... ?

post-37120-0-88687100-1346451202_thumb.j

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Shadrack    601

Whenever someone tells me that a computer went bad because of bad capacitors, I usually interpret that as they can't figure out what really is wrong so they are blaming bad capacitors. It's kind of a catch all for bad motherboard :/. I'm not saying it doesn't happen.

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zeta_immersion    68

I have seen blown capacitors before but the system was running ok under light load (email and random stuff) .. eventually it died .. told the user to go buy something better .... cannot deal with cheap crap people buy from Costco and they rave about as if it is the latest model that came out last minute.

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sc302    1,439

Whenever someone tells me that a computer went bad because of bad capacitors, I usually interpret that as they can't figure out what really is wrong so they are blaming bad capacitors. It's kind of a catch all for bad motherboard :/. I'm not saying it doesn't happen.

Don't work with pcs much do you? When capacitors blow, esp around the processor, it will produce some interesting results from random blue screens to being very slow to respond, to not coming on at all. If you are on a computer and it feels like someone turned on a heater under the desk, also with slow or no response and blue screens, I would be you a bag of donuts that the caps are done and the cause of your issues....If you went to reinstall the os, it may not even install (it would bomb constantly during the install process). Dell sff's are good for that.

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+goretsky    717

Hello,

It has been a while since I have seen any motherboards with bad capacitors but when I did, they were usually around the ATX power connector or the AGP slot. Residue varied in color from red to brown to black.

Regards,

Aryeh Goretsky

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f0rk_b0mb    698

Umm...Just took a second look at my above post:

My joints are never perfect.

LOL!

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