First I’d just like to confirm that this blog is not dead or dying: The reason that there haven’t been quite as many posts appearing lately as there used to be are computer problems the last two weekends and illness the weekend before.

A capacitor is, in basic terms, an passive electronic component that stores electrical energy between the tiny gap between two electrodes. They have many different uses; and it’s rare to find a piece of electronic equipment without a capacitor or capacitors in it.

One piece of electronic equipment where a lot of capacitors are used is your computer, where there are quite a few. You’ll find them on any board, and in particular inside the power supply unit (PSU). There’s a certain type of capacitor called an electrolytic capacitor that uses an electrolyte between the electrodes or plates in order to increase its capacitance. The circuit-board mounted electrolytic looks like a tiny bean-can of varying size and height on a circuit-board.

When an electrolytic capacitor is made with good-quality materials it has a fairly good mechanical rigidity despite its high potential for electrical leakage. When a capacitor is made on the cheap, however, problems occur, and its working life is limited. Unfortunately there’s no way to tell how long an electrolytic capacitor will last if you’re not familiar with the manufacturer. The electrical characteristics of any new capacitor will be as marked on the tin, in all but a very few cases. It’s only with use that things start to go pear-shaped.

Since around 1998, some motherboard and PSU manufacturers have been using Chinese-manufactured ultra-low-cost electrolytic capacitors in the construction of their products in order to keep costs down. This has led to something that is known these days as "capacitor plague":-

Capacitor plague occurs after around a year or more of in-circuit usage of a low-quality electrolytic capacitor. Because the chemical formula for the electrolyte used in the capacitor is basically the cheapest formulation that the manufacturer could get away with and have their product still function; eventually, with use, hydrogen gas bubbles build up in it between the capacitor’s plates. This increases the internal pressure within the sealed can. Eventually the pressure builds to a point and the electrolyte/gas bubble mix escapes any way that it can: This could be from the base of the component; but more usually from the top, where usually a weakness is deliberately built into the electrolytic capacitor’s can so that any venting electrolyte can escape from the top. The main reason why it’s better that it escapes from the top is so that a visual inspection of the faulty circuit easily identifies a leaking electrolytic.

(Of course things haven’t always been this way. Perhaps you might remember the old 1940/50s television sets, where due to lower capacitor technologies at the time, huge capacitors, literally the size of a bean-can or larger, were used in places without any place for the expanding electrolyte to go. Older readers perhaps may recall their television making a huge bang; blowing the back off and leaving a cloud of acrid smoke. That was just a capacitor reaching the end of its life – Usually rendering the whole unit inoperable and beyond repair.)

Many motherboards and cheap power supplies manufactured between 1998 and 2007 incorporate these cheap and nasty electrolytic capacitors, and many fail rather quickly. Commonly there’s no massive bang, although it has been known even in computers. More than likely the faulty cheapo capacitor either bulges, leaks, or both.

If a motherboard or other device suddenly begins playing up; take a look at it and check the capacitors: If the can on any given capacitor doesn’t look perfectly-formed, or if you see a rust-coloured mark on it, or both – usually at the top – then you can assume fairly correctly and with a good degree of accuracy that your device has capacitor plague.

There is a cure; but it could be rather long-winded and not worth the hassle, in replacing all the faulty and potentially-faulty electrolytic capacitors on a given board. This is usually ultra-geek work and requires a good and steady hand at soldering, plus some knowledge of electronics and electronic circuit construction in practical application. I’m trained to that level myself, in fact beyond that to military-grade soldering standards, but in my opinion it’s much easier to buy a new board than attempt the fiddly and not-always-successful task of replacing capacitors.

It’s a shame that this happens and has been allowed to continue unpenalised for a long time; but it does, it has, and there’s not-a-lot can be done about it. These days many manufacturers, Gigabyte in particular I notice, are manufacturing their products using non-electrolytic capacitors – Thus avoiding the chances of capacitor-plague. However some are still using electrolytic capacitors in the board’s component population, and, who knows, they could be made in China and cost ten-a-penny?

What do you think? Should companies continue to cut costs and quality too just for the purpose of making their products slightly cheaper? – After all it’s the customers who suffer, not the protagonists.