Page 95 - Testing Electronic Components

There are three ways to discharge the large filter capacitor in a switch
mode power supplies.

Please don’t use this method to discharge filter capacitor

Discharging the capacitor with a screw driver (not recommended).
The reason for not using the screw driver to discharge a capacitor is
because the printed circuit board or circuitry can be damaged due to the
spark generated while discharging the high voltage in the capacitor. I
once have blown the power area using this method. However, if you
knew that the capacitor stored voltage is not too large after confirmed it
with a meter, you can easily discharge it with a small screw driver.

Just place the screw driver tip to touch the two pin of the capacitor,
within seconds the charge will be gone. If the capacitor holds a heavier

charge of electricity then discharging the capacitor with a screw driver
may melt the tip of the screw driver and the copper on the printed circuit
board. Sometimes a big spark may cause small disintegrated solder lead
or copper to fly out from the circuit board and might injured your eyes or
body.

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