How to Discharge a Flyback Transformer

Written by richard asmus
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A flyback transformer creates high voltage to operate cathode ray tubes (CRTs) in television sets and other appliances. Since CRTs can store the high voltage even after unplugging the television, you need to discharge the high voltage to create a safe working environment. If you do not discharge the high voltage, you could get a nasty shock. To discharge the flyback transformer, you must have the ability to remove the back cover of your television set and find the anode of the flyback transformer. You must also be able to find chassis or “cold” ground within the set.

Skill level:

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Things you need

  • Test lead with alligator clips at both ends
  • Screwdriver with insulated handle

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  1. 1

    Connect one alligator clip of the test lead to metal shaft of the screwdriver.

  2. 2

    Connect the other alligator clip of the test lead to the metal chassis ground of the TV set.

  3. 3

    Touch the screwdriver to the anode of the flyback transformer. The anode is a rubber or plastic cap that is connected to the top back of the picture tube. Push the screwdriver up under the cap so that it touches the metal connector underneath the cap. You should see a spark and hear an arcing sound (a sharp snap) as the transformer discharges.

  4. 4

    Remove the screw driver. Wait a minute, and then repeat. Because the picture tube acts as a capacitor, it can still have some charge left in it. Leave the screwdriver in place touching the metal connector under the anode cap for at least one full minute to ensure the high voltage system is completely discharged.

Tips and warnings

  • Circuits in some computer or video monitors automatically discharge the flyback transformer when turned off. On these you may not need to discharge the flyback transformer, but it's safer to go through the process to make sure. The flyback generates over 10,000 volts and any residual storage can deliver a very nasty shock.
  • Do not touch the anode of the flyback transformer with your bare hands until after you have discharged it.
  • Do not attempt to open a television set--or any other appliance with internal high voltage--to work on it unless you are a qualified technician.

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