Why does turning an electronic device off and back on again work?

If you can, please explain why turning an electronic device off then on again works so often when the device stops working. What is causing it to stop working? Why does turning it off then on again work? Why do you have to wait a period of time after turning it off before you turn it back on again? How do you determine the amount of time you should keep something off before turning it back on again? Why is the amount of time necessary different with different devices? What is the most common problem that this solution resolves? What is the process that is actually occurring inside the device when you do this?

3 Answers

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  • 7 years ago
    Favorite Answer

    Ok, here it is.

    Most devices which are more complicated than an electric jug these days are controlled by a microcomputer chip. When you press the buttons, tiny "instruction" voltages are applied to various pins on the chip, which reacts by (for example) initiating larger signals used for turning the device on or off, adjusting volume up or down, whatever. These "control" signals take a small but finite amount of time to disappear once they have done their job.

    Sometimes (perhaps due to a power surge, or too many buttons pressed at once, or too quickly, or a stuck button, for example) the chip finds itself with conflicting control signals, or "instructions". It doesn't know what to do. Sometimes the "instruction" voltages do not drop off as quickly as they should, (or at all, if the device is poorly designed or if a button is stuck). The next instruction conflicts with the last, or "stuck" one, and the chip just "spits the dummy" and locks up the device.

    In general, devices of this type have power supplied to the chip even when it is notionally "off", so it can respond to the buttons (or a remote sensor), so as long as the device is connected to power, the "lock-up" will continue.

    Switching off the device (by unplugging the power source) and leaving it off for a few seconds (generally between 10-30 seconds), allows these conflicting instructions to disappear, and the device usually restarts quite happily.

    I have found that sometimes pressing all the buttons one after the other while the device is powered down, is helpful if simply restarting doesn't work.

    My experience has been mostly that the cheapest device in any category is more likely to suffer these problems. One of the ways you get what you pay for...

    Hope that helps.

    Mike

    Source(s): 50 years electronics technician.
  • ngufra
    Lv 4
    5 years ago

    electronic devices are state machine. If it's stuck in a bad state it may not get out off it on its own.

    Turning it off and on again forces it to start again from an initial step and do a known set of state changes. it puts it back in a good state.

  • 7 years ago

    it restarts the whole device

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