How to Disconnect a Cable From a TV With Flyback Transformers
To repair your older CRT (cathode ray tube) TV, you may need to remove one or more of the small wire harnesses attached to the power supply board. This critical circuit board houses high-voltage capacitors that supply power to the flyback transformer, a device that controls the horizontal scanning beam in CRT TVs. In order to safely remove any associated cables, circuit board or the transformer itself, you must first discharge these capacitors to avoid a shock hazard.
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Things You'll Need
- Screwdrivers (Philips, Torx or Allen)
- Ground strap
- Fiberglass capacitor discharge tool
- Needlenose pliers
Instructions
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1
Turn off and unplug the television. Remove the back panel by first removing the screws around the perimeter of the set, using the appropriate screwdriver. Set the panel aside.
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2
Locate the power supply board near the flyback transformer. Identify the transformer by looking for a 2-by-6-inch black plastic or metal box, usually housing two or more small adjustment knobs. There are normally larger red or yellow wires leading from the power supply board to the transformer.
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3
Identify the nearby power capacitors requiring discharge by noting that at least one of them is significantly larger than the smaller ones surrounding it.
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4
Put the ground strap on around your wrist. Attach the alligator clip to a piece of metal on your desk or workbench. Do not ground back to the television's chassis.
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5
Extend the fiberglass capacitor discharge rod's arm. Attach the discharge tool's clip to the desk or bench. Remove the rubber protector over the metal discharge hook, if present.
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6
Gently touch the two legs of each primary power supply capacitor. Note the spark and possible "pop" sound as the capacitor(s) discharge. This is normal. Repeat as necessary until no further sparking occurs.
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Gently pull the white or black wire harness plugs from the primary circuit board, using the needlenose pliers. Remove the circuit board, if required, using the appropriate screwdriver.
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Tips & Warnings
Never attempt to service an appliance with electrical power supplied to it. This may result in electrical shock.
References
Resources
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