Content
This article explains a technique that can be dangerous and potentially deadly in some situations, especially when operating at high voltages. It can work with a battery powered radio, but the microwave in the picture has a high voltage capacitor in the microwave dual circuit, which can have a charge of 1 kV or more! Capacitors can be found in many electrical appliances and electronics. They store excess electrical energy during power surges and discharge energy during a shortage to provide the unit with a constant, even electricity supply. The larger the capacitor, the more charge can be stored in it per voltage unit, even after the unit is turned off. However, this is not to say that smaller capacitors are all harmless. Before you start tinkering with a device or an electronic device, you must first discharge the capacitor; in this article you will find instructions on how to safely discharge a capacitor.
To step
Learn to use the correct techniques and equipment for working with electrical equipment. Never let your hands come unprotected to anything that might be under tension. 
Disconnect the device from the mains with the capacitor. Alternating current will continue to flow through a capacitor until the power source is disconnected. That current can add to the shock you get if you mishandle the capacitor, and can continue to charge the capacitor. 
Find the capacitor. Most capacitors are made up of two conductive plates separated by an insulating plate; more complex capacitors are provided with several layers of metallized plastic. Large capacitors (the most dangerous) are usually cylindrical and look something like battery cells. 
Remove the capacitor from the system, if it is not soldered on. This way, damage to the circuits can be avoided when you discharge the capacitor. - If it is interchangeable, it is likely to be very large and potentially very dangerous.
Touch the capacitor contacts for a few seconds with a component. This creates a path for the electricity to pass and allows the capacitor to discharge. You can use a resistor of 5 to 10 watts, a voltmeter, test light or an ordinary light bulb for this. - A voltmeter or light can show the progress of the discharge, either with a digital display or a gradually dimming bulb.
Tips
- Once the capacitor is completely discharged, keep the contacts connected to a resistor or piece of wire to keep the capacitor discharged.
- Capacitors will discharge on their own over time, and most will likely run out of charge after a few days, as long as there is no external power supply or internal battery to recharge the capacitor - but always assume the capacitor is charged, unless you have confirmed otherwise. The device must not be connected to the mains voltage, nor must it only be "switched off".
- Do not try to discharge the capacitor by licking your fingers and then touching both contacts! This will shock you!
- Do not hold the resistor in your hands, but use a test board or wire.
Warnings
- Large capacitors are very dangerous and others are often in close proximity to one you want to work on. Tinkering with it is probably not the best idea for a regular hobbyist.
- While it is possible to connect the ends of the capacitor with a small screwdriver, the amount of current through the discharge can melt the tip of the screwdriver, or the copper on the PCB, if the capacitor is still connected. Large sparks, in particular, can burn power supplies or turn molten copper or solder into a projectile that can injure you.
Necessities
- A resistor, voltmeter, or light bulb (to discharge the capacitor)
- Electric wire (to keep the capacitor discharged)
