Capacitors what?

So you consider yourself a hardcore IT techie. There is no computer issue so far that you couldn’t sort.

Not only you know the Windows registry like a walk in the park, you also know everything about networks, security and encryption. Linux? Hah… forget that! You compile your own BSD box, and can hex edit your file-system and patch firmwares and BIOSes. People consider you the utmost authority in computers. Nevertheless, you can’t figure out why that computer keeps hanging on you. You tried to format the PC, you swapped RAMs, CPU, tested all expansion cards; yet you simply can’t tell what is going on.

Perhaps you’re starting to doubt your IT skills, or are simply shouting obscenities to the computer’s open carcass in rage and frustration. However, the question you should be asking yourself at this stage is not how much you know or think you know about IT, but know much you know or think you know about electronics?

Altough IT is a science on its own, many ‘self-made IT gurus’ tend to make the (honest) mistake to forget that first and foremost, the world of computers is governed by electronics. Like IT, electronics is a fascinating, complex and broad science that studies “the flow of charge through various materials and devices” (Wikipedia, 2008).

What are they?

One particular component I would like to draw your attention to is to capacitors. In dummy terms, capacitors are in a way like little bateries, as they store electric energy between a pair of conductors (called plates). These plates are separated by an insulator (i.e.: non-conductive material) known as dielectric. Dielectrics can be, in theory, any non-conductive material such as air, porcelain, chemicals (e.g.: electrolytes) and teflon. Besides storing energy, capacitors can have other applications such as filtering, signal processing and power conditioning; and the type of dielectric implies for what application it would be best used for.

What is the problem?

The thing is that capacitors can age, particularly the electrolytic ones which use chemicals as its insulator. A while ago I was having a hard time with a computer I built. The system would simply freeze when my soundcard emited a sound, when I moved the mouse or at other simple tasks. I formated and reinstalled the operating system several times, troubleshooted all expansion cards and drives, tried different operating systems and flashed the BIOS; yet nothing worked. After opening my computer for the 100th time, I noticed that some of “those little aluminium cylinders” in my motherboard looked funny. After replacing the motherboard (which was out of warranty), everything started to work as it should. Here are some visual sympthoms of capacitor problems which I witnessed:

  • Swollen or bulged caps: When the ‘top’ of the capacitor looks like its bulged. This is due to presure being built inside it.
  • Leaking substance: When you can see a substance (mostly a black or brown crusty substance) coming out of it. That is the electrolyte, and yep: It shouldn’t be coming out!

What should I do first?

If your system and/or the failing component is under warranty, your first option should be to activate the warranty and have it repaired or replaced. For those with components out of warranty however, replacement can be quite drastic. Particularly if the problem is narrowed to a few capacitors. However, the best remedy is prevention. Here are some pointers on how to prevent being a victim of capacitors plague.

  • Temperature: Keep your system cool. Electrolytic capacitors are sensitive to temperature and they will age faster if your system is too hot.
  • Solid Capacitors: Look for motherboards and other components with fewer electrolytic capacitors as possible, as solid capacitors are more resistant to temperatures and more suitable for high-frequency applications.

However, certain systems could be simply doomed to failure due to poor design. I have a Linksys WAG54G v2 ADSL router and I noticed that its switched ports wouldn’t work with 1Gb network adapters unless I forced them to 10Mb (no, forcing to 100Mb wouldn’t work either). I did some research on the internet and a narrowed down the problem to (you probably guessed) capacitors. Basically the WAG54G was poorly designed and it overheats quite a lot, thus damaging the capacitors.

What should I do next?

Problem is, once a capacitor is damaged there is no other option rather than replacing or repairing the unit. This is why I am currently on a mission to learn a little bit more about electronics; at least enough to be able to test for defective capacitors (and other components) and learn how to replace them. And my suggestion to all other IT gurus out there is to do the same. The good news is that there is a lot of information on the Internet for us to get started. Here are a few ones:

  • Wikipedia – Capacitors: This article will introduce you to capacitors, what they are, the different types, their applications, etc.
  • – How Capacitors Work: If the previous article was little too much of a heavy reading you might want to check this one first (this is not a criticism! I read this one first as well).
  • Wikipedia – Capacitors (component): This article gets a little bit more pratical as it discusses in more detail the different types of capacitors, their applications and their disadvantages.
  • Wikipedia – Electronic color code: Believe it or not, electric components aren’t coloured just to look cute. Those colours actualy have a meaning, and understanding them would help you know the value of the capacitors (and other components such as resistors) in order to replace them.
  • Wikipedia – Capacitor plague: This article discusses the premature failing of capacitors, giving a particular emphasis in computer electronics (e.g.: motherboards). It also gives some background information about the infamous industrial spionage case that plagued Taiwan with defective capacitors.
  • Silicon Chip Online – Motherboard Capacitor Problem Blows Up: This article gives some good background information about the capacitor plague epidemic of the early 2000s that pestered several motherboard manufacturers.

I’m up for it!

Ok, so you had enough of theory reading and you want to get your hands dirty. Fair enough! First things first, consider that you will have to get a good set of equipment such as a good soldering kit, desoldering tools and of course: quality capacitors. In the UK, a good place to by all this equipment is Maplin. But before you start taking your credit card out of the wallet, I strongly recommend you visit It is the best site I found so far with tutorials, pictures, suggestions, etc.

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