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Science

How to Find Bad Capacitors in a TV

mb/The bulging capacitors in the middle are a common electronics problem.
The bulging capacitors in the middle are a common electronics problem.
Credit: Matthew Bystedt

Has your TV stopped turning on? Does it cycle and click like mine did for multiple times before finally turning on? You have likely got bad capacitors like the ones above.

What is this mystery part that has turned your friend, the boob tube, into a hunk of unreliable (or unusable) plastic junk? A capacitor is a small device used to store electric charge in electronics. A properly working one alters electric signals so that our electronics work. Capacitors with bulging tops (or even blown wide open) no longer function how the electrical engineer intended the device to operate.

Bad capacitors are a huge problem in the electronics industry. While it's a neat party trick to stick a ballon to a wall, this illustrates the point that electric forces are many times stronger than even gravity. Imperfections in the capacitor can cause it to explode as those forces overcome the physical strength of the capacitor. This is why radial electrolytic capacitors are scored with an x on top. These weak points are a safety valve that allow the capacitor to "gently" explode with a pop or snap sound. Besides causing physical damage, a bad capacitor can leak and actually short out other components.

Locating a Bad Capacitor

If your equipment is under warrantee, take it to your local service professional for repair. Taking something like a TV apart is for someone that is curious and understands that they may break it. Looking at a couple pictures on the internet does not make you an expert.

Safety first! Always turn off and unplug a TV before opening it. It's a good idea to wait before opening it up. Components (like capacitors) can have potentially lethal amounts of charge stored up in them. The stored charge will leak and the TV will become neutral after a number of hours. I'm being vague here as it's impossible to say how long it will take. If you're worried then just leave it overnight.

mb/Start by laying the TV down on a flat surface and remove the back panel. It helps to layout the screws how you found them.
Start by laying the TV down on a flat surface and remove the back panel. It helps to layout the screws how you found them.
Credit: Matthew Bystedt
mb/There will likely be some kind of cage. Remove it and unclip any cables in the way.
There will likely be some kind of cage. Remove it and unclip any cables in the way.
Credit: Matthew Bystedt
mb/We can now see all the capacitors and see which ones are bad.
We can now see all the capacitors and see which ones are bad.
Credit: Matthew Bystedt

Radial capacitors are the tall round components on a circuit board. A bad capacitor is usually easy to visually spot. If it hasn't exploded (lucky you) then the flat top will be dome shaped and the X will have split open.

mb/If you are lucky the bad capacitors are on board that can be removed. Good luck screwing everything back together again!
If you are lucky the bad capacitors are on board that can be removed. Good luck screwing everything back together again!
Credit: Matthew Bystedt

If you're feeling really adventurous then, at this point, you can order replacement capacitors. The Samsung LNT-4669 pictured here was part of a group of similar TVs that all had bad capacitors. In some cases, sets of replacement capacitors for your model can be bought online. This is the point where I took out the soldering iron and replaced the damaged ones. It was the some of the easiest soldering that I've ever done. Always replace capacitors with same capacitance (uF). The temperature and voltage ratings can be higher than the original. The only other issue is that they have to fit.

mb/This capacitor is clearly damaged and replacing it allowed the TV to work again.
This capacitor is clearly damaged and replacing it allowed the TV to work again.
Credit: Matthew Bystedt