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The Most Common Reason All Electronics Fail
By Ted Twietmeyer
How this happened to you? You go out to your vehicle, get in and turn the key and nothing happens, or you hear the starter rapidly clicking. You know you car battery is dead. No lights were left on and nothing you know could have caused it. Logically you think the problem is a dead battery and you are partially correct. But lead-acid car batteries almost never suddenly stop working. Most likely the problem is the alternator or in very rare cases, wiring between the alternator and battery. Alternator was unable to charge the battery the last time you drove it. Alternators are the power supplies for all vehicle. Believe it or not, alternators actually have two brushes inside - much like a vacuum cleaner motor has.
Perhaps you bought a new flat panel or computer monitor. Not long after the warranty runs out, one day suddenly it will not turn on. For no apparent reason it just quit working. You check the connectors, the wall outlet and even the plug strip if you use one. Everything works but the panel. That tiny little light on the panel does not light up. Why? Almost 100% of the time, the problem is the power supply inside the panel. Dead pilot is the big indicator. If the power supply has failed, you will not see that light even in standby.
In the case of a computer monitor, it might be the black plastic block which is part of the power cord. Consider yourself lucky if all it does is quit. There have been power supply blocks from Dell that catch fire for no apparent reason. At least one university banned Dell power supplies for that reason. Common reason this can happen is under-engineering the power supply. These units can run so hot when badly designed, they ignite the plastic. Consider plastic softens at about 400F. That gives you an idea how hot these flames are - more than enough to burn down your office or home. Remember that all plastics are derived from oil...
Like your vehicle which uses an alternator for the power supply, the flat panel power supply is the most common part that fails. Inside a TV are literally thousands of connections between chips and the glass panel, and dozens "chips." But these rarely fail. Often the part that fails is part of the power supply board - usually an electronic component worth just a few dollars or even less.
Back in the analog television days, it was almost always the power supply circuits that would fail. Even in vacuum tube days. Solid-state Sony televisions back in the day frequently had a small $1.98 device that failed in the power supply, disabling the TV. One lightning strike also has fried these parts, when the surge came in through the antenna connector.
Both old analog televisions and flat panels are susceptible to lighting strikes and power surges. Now you know enough to guess what usually fails in a microwave oven. Yes, the power supply; a small high voltage diode for the magnetron that costs just $3.00.
By now you must be asking, "Why aren't products designed better so this won't happen?" It all comes down to cost of manufacturing. Often power supplies in products are under-designed, engineers use cheap components to meet cost objectives or are power supplies are inadequately ventilated to remove heat.
So now you know. If your flat panel is cracked or develops permanent stripes when operating, that's a bad problem with the screen itself or the dozens of chips that drive the screen. Truth is that is probably not worth the repair cost, and it must be sent back to the manufacturer. But if it suddenly stops working and a serviceman or shop tells you, "You need a new screen" or some other extremely expensive repair now you will know he's lying to you!
What does NASA and the military do for this problem? They use redundant power supplies in everything critical. There are two power supplies always operating, always powering the system. Either power supply can fail but that does not matter. Only one supply is required to keep the system operating. The failed supply is simply replaced without taking the system down.