A flyback transformer is a critical component in rear-projection televisions. The transformer provides the high-voltage output that is necessary to produce a clear, continuous image on the screen. A failing flyback can result in a blurry or distorted image, hissing or whistling noises while the television is operating, and a complete loss of image or failure to power up. The flyback transformer itself is usually inexpensive; however, the effort and expertise needed to replace it are considerable.
Things You'll Need
- Inspection mirror
- Test clips
- Soldering iron
- Desoldering braid or suction bulb
Unplug the television; if you've never discharged capacitors or other voltage-retaining components, leave the TV unplugged for a week or longer before attempting this procedure. Remove the front and rear service panels on the television with a screwdriver or, depending on the model, remove the entire rear shell. Locate the flyback transformer; it is a large component, soldered to one of the circuit boards, with two or more red cables attached to it.
Mark the location of all the wires, cables and screws attached to the board with the flyback transformer. Disconnect all the wires and cables, except those connected directly to the flyback transformer, and remove the screws. Look for any clips or tabs holding the board in place and remove them. Trace the wires and cables connected to the transformer and mark their locations at both ends.
Inspect the connection points both on the transformer and at the cable terminations. Determine whether your television model uses a cathode ray tube (CRT); if so, one of the cables will terminate in a flat rubber plug on the back of the CRT. Discharge the CRT before removing the cable by connecting a test clip to the metal shaft of an insulated, flathead screwdriver; connect the other end of the clip to a metal part of the TV chassis. Gently pry up the edge of the rubber plug and work the blade of the screwdriver under the plug and toward the middle of the plug; when you reach the middle of the plug and contact the cable conductor; you should hear an electric "snap." Leave the screwdriver in contact with the conductor for several days to allow the CRT to fully discharge. Pry the rubber plug free from the CRT and gently disconnect the cable.
Inspect the connections for retaining clips; remove any clips to release the cables; if no retaining clips are found, the cables may be twist-locks. Grasp the cable near the connection, push it further into the connector, and twist it 90 degrees counterclockwise and try to pull it out of the connector. If the cable still does not release, it may utilize a friction lock. Remove the friction lock connection by pulling on the cable. Grasp the cable tightly with one hand or pliers and pull on it while supporting the component it's connected to with the other hand. Pull the board out of the TV chassis after all the cables are disconnected and take the board to a well-lit area for desoldering.
Place the board upside down on a workbench or counter. Identify the location of the flyback transformer pins. Heat one pin at a time carefully with the soldering iron until the solder liquefies. Remove the heated solder with a desoldering braid or suction bulb. Pull the transformer off the board once all pins have been fully desoldered.
Tips & Warnings
- A failing flyback transformer can cause numerous problems, including damage to other internal components. Replacing the transformer may just be the first step in the troubleshooting and replacement process.
- If you have little or no soldering experience, practice on spare parts before attempting to repair the sensitive components inside a projection TV.
- Dangerous voltages can remain present in a television for weeks or months after it has been unplugged. Treat every circuit as if it were live until proven otherwise.
- "Illustrated Dictionary of Electronics"; Stan Gibilisco; 2001
- Photo Credit tv control and tv 3 image by chrisharvey from Fotolia.com
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