Tip & How-To about General Computers & Internet
Electrolytic Capacitors are something to keep note of when troubleshooting computers that crash. Symptoms can be: Will not boot, have distorted or no video, randomly shut off or on, distorted or no audio, or just do random and crazy things. Electrolytic capacitors can be found on a lot of electronic circuit boards (motherboards, video cards, sounds cards, power supply boards, network cards, etc). They look like a long cylinder with a stripe down one side indicating the negative polarity lead.
When looking for bad capacitors always check the motherboard first. The motherboard will typically have electrolytic capacitors around the processor. You then want to look at the card directly involved with the failure. If everything still looks good, then it can also be in the power supply. With general symptoms and where to look: Issues with powering on and off (motherboard and power supply), issues with video (motherboard and video card), issues with sound (motherboard and sound card), and etc.
Some general tips on recognizing a bad capacitor is looking at the top and bottom. The top should be flat, so if you see it bulging out, then it's bad. You also want to look the tops and bottoms over for any brownish substance leaking out. This substance is the electrolytic part of the capacitor and it can do damage to circuit boards. It can eat through traces, solder pads, through holes and cause opens that can't be fixed. Any time you see this on a circuit board, look it over very closely for damage after you remove the capacitor and clean the electrolytic off. I just use rubbing alcohol on a Q-Tip to remove electrolytic from a circuit board. Some manufactures use glue, epoxy, or silicon on parts to bond it to the motherboard. Don't confuse glue for a leaky capacitor. That stuff should be hard and not clean off with rubbing alcohol.
Electrolytic capacitors are usually easy to replace using a soldering iron, solder wick, solder, and side cutters. Make sure you put the new capacitor in with the stripe on the same side as the one you took out. If you don't, it could explode. Always wear safety glasses!
For more information about electrolytic capacitors, troubleshooting, getting parts, and replacing them, go to this link: http://www.capacitorlab.com/index.htm
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