How to Discharge High Voltage Mains in Color TV
Color televisions, especially of the cathode ray tube (CRT) variety, tend to maintain rather high voltages in the mains capacitors even after the set is turned off. Capacitors in these televisions store enough charge to activate the television after the power button is pressed. Regardless of the television type whether plasma, CRT or liquid crystal display, you do not want these potentially lethal voltages present if you attempt to service or troubleshoot the set yourself. Use a proper capacitor discharge tool to perform the task safely.
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Things You'll Need
- Screwdrivers (Philips, Allen, Torx)
- Capacitor discharge tool
- Grounding alligator clip
Instructions
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Unplug the television from the wall. Unscrew the back of the set, using the appropriate screwdriver. Locate the primary mains capacitors on the CRT board. Use the television schematic if these are not clearly labeled on the board itself.
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2
Clip the grounding wire's alligator clips to a metal portion of the set's chassis and to the capacitor discharge tool. Extend the fiberglass wand of the tool.
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3
Touch the two leads of the capacitor simultaneously with the metal probes on the fiberglass end of the discharge tool. Watch for a pop or crackle. This is normal. Repeat as necessary for each mains device until the capacitors no longer emit a charge.
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Tips & Warnings
You can assemble a capacitor discharge tool using a 100 millivolt capacitor soldered to the end of a fiberglass rod if a proper tool is not available.
Do not use a screwdriver or other homemade tool to discharge a capacitor. High voltages are potentially lethal to you and damaging to the screwdriver.
The old field repairman's trick of sticking a screwdriver or other metal insulated tool under the rubber shroud of the mains caps is potentially damaging to the capacitor.
References
Resources
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