Aging Components

Solid state electronic components seemed to me like a liberation from the problem of wear and tear. Any product containing mechanical parts has been subject to wear and the limited lifetime of those mechanical products has been something obvious and natural. Solid state has brought the new concept of "no moving parts" and to many it was like "finally these products can live forever". 

Unfortunately "forever" for typical electronic solid state products means just a couple of years. And capacitors are in most part responsible for this failure. Initially I thought this problem applied only to electrolytic capacitors, which I have been regularly replacing in some of my aging gear.

Recently, however, I have experienced a couple of failures of the so-called "actor" modules in my smart home system. These actors are small electronic cubes mounted in walls behind regular wall switches. They are a great way to upgrade an analog electrical installation to a smart one. They have a bunch of electronic components inside (typically a pair of MOSFET transistors, a microcontroller and a digital radio circuitry). They of course need a power supply circuit, so to reduce space (and cost) a simple circuit with a high voltage capacitor is used. These capacitors are made of polypropylene film.

And though not so quickly as the electrolytic ones, these propylene capacitors still lose their capacity and at some point the electronic circuit stops functioning. In my case this  was about 10 years. Which seems to be fairly long but in fact it is not. Many things like light switches are expected to just work forever. And now it turns out a mechanical switch (despite the wear and tear) can easily outlive an electronic equivalent.

What is worse, these little cube modules are not designed to be serviceable. So you are expected to throw a broken one out and buy a new one. Typically around $50 a piece. While the failed capacitor inside costs less than 50 cents. 

I have already resurrected a handful of these actors, cutting their tightly sealed enclosures with an ultrasonic knife (one of the most powerful tools in my toolbox) and replacing the 50c part, then putting the enclosure together with a help of a heat-shrinking tube. 10 more years of life or maybe more.