After initial run in electronics are pretty stable ( but you better have spike, surge, noise, and overvoltage protection on your AC lines ) Failure points mostly center around capacitors and there in lies the rub. It is almost impossible to get any idea of the quality of the caps used on the circuit boards. Best example I can recall is Dell computers- with very cheap caps installed, having a very high failure rate at about the 1 year mark- Samsung is /was another co. with a similar problem. Atmospheric terminal corrosion is another area that causes problems- one that you have little or no control of as it concerns the quality and type of material used in/on the terminals. Electronics function well in most common design specs in the same temperature range, air quality that you prefer. Cold and heat out side of normal human range must be specifically designed for with cold being the lessor of the evils. Electronics must be isolated from high heat factors and/or have multiple ways of dissipating same otherwise at some point breakdown of the internal structures occurs causing catastrophic failure. ( clear as mud eh?)
OOPs, forgot: Roughly a 10 year lifespan on good caps then the dielectric properties internally start to degrade at a very rapid rate.
