Capacitor Plague

Over the years, probably many of you have experienced failures of consumer electronic devices. Power supplies, internet routers, game consoles and personal computers. During the last 12 months I have had an unusual number of such failures. Two satellite receivers (Kathrein UFS-910). Three plug computers (Sheeva Plug Development Kits). Three wireless routers (ZyXel Ethernet-Over-Powerline). That is eight devices in one year. Pretty unusual statistics. Enough to trigger my curiosity to conduct a forensic investigation.

All those failures obviously had an number of things in common. Firstly, all failures were at power supplies circuits. Bam, and all of the sudden the electronics were not receiving the regulated supply voltage. I quickly recalled the failed devices were running quite hot prior to the failures. After opening the cases I found burst electrolytic capacitors. And replacing the capacitors fixed the problems.

First - I thought - bad design. Electrolytic capacitors are quite sensitive to operating temperatures. Heat them up and they burst. They even have a temperature rating. In all my cases I noticed the capacitors were rated at 70 degrees Celsius. The temperature never got that high, but it seems it got high enough to make devastating changes over the period of several months. When I went to the local electronics shop, I learned they had capacitors rated at 105 degrees Celsius. Capacitors are generally quite cheap. What was my astonishment when I learned the 105C rated ones are only 20% more expensive. And we are talking about price ranges of 10 - 12 cents! Later I was told the 105C rated have orders of magnitude longer life.

So yes, bad design. First, when there are heat - sensitive components, the devices cannot be designed to heat up when they are plugged in. Because, as my example shows, such approach is a guaranteed failure. Second, witch such a tiny price difference (we are talking several cents in devices selling at $100 or more), it is simply stupid to use the worse components. It is selling your - the manufacturer's reputation, cheap.

And then I found the Wikipedia article on the Capacitor Plague. How surprised I was to learn the problem is on a global scale, and is even linked to industry espionage. Wow... Interesting... I wonder how many devices failed worldwide because of this?