Projection TV convergence and repair

Week 24, 2003

Q) My husband and I “inherited” a big screen projection TV from my in-laws. It is around eight years old and the picture looks good, but it has two problems. First, people and objects have colored fringes or shadows around them, like you are watching a 3-D movie without wearing the special glasses. Second, there is a circuit breaker on the back that we have to push a certain way to get it to work. If we push it in all the way, the TV will shut off as soon as we turn it on. If we push it in partway, it will stay on for a while before the TV turns off. Any idea what is wrong, and should we have a repairman look at the TV?

-Nicole Cox, Canonsburg, PA

A) If you plan on keeping the TV, you should have an authorized service person look at it before you try using it again. Televisions, especially rear-projection televisions, get very hot and work under very high voltage. Electrical problems can create a shock or fire hazard, and that is why your TV has a circuit breaker. The circuit breaker is a safety device designed to activate and cut power when it detects an electrical problem. If it needs reset repeatedly, your television definitely needs servicing. There is no telling how much the repair will be, but it is likely to be much less expensive than buying a brand-new projection set. It is worth the cost of a service call to get a repair estimate and an evaluation of the TV’s condition.

The reason you are seeing the colored fringes is because the TV’s picture tubes are very slightly out of alignment, commonly called convergence. Unlike the single direct-view picture tube we commonly associate with television sets, rear projection TVs use three tubes, one for each of the three primary colors: red, green, and blue. These three tubes project three separate images that merge together on the screen to produce a full-color television picture. The images must match up exactly for the picture to look right and the tolerance for error is very small. When you moved the TV from your in-laws house to your home you may have knocked the tubes out of alignment a little bit. Not to worry- except for late-model TVs with automatic convergence, all projection TVs need to have their convergence fine-tuned from time to time. With this in mind, manufacturers make it easy for you to set the convergence yourself.

If you access your TV’s setup menus using the remote control, you should see a setting for convergence in the video menu. Though there may be variations from brand to brand, generally the convergence process is the same. When you activate convergence from the video menu, each of the separate picture tubes will project a crosshairs on the screen. Using the buttons on the TV or the remote control, you line up these red, green, and blue crosshairs until you have a single white crosshair on your screen. This is color theory at work; equal amounts of red, green, and blue light create white light. When you have a single, white, non-fringed crosshair, the tubes are aligned and will produce a proper television picture.

I have explained this process so you can check and converge the TV yourself when the need arises. Please do not attempt to converge your TV until you have it fixed! I imagine when you have the TV serviced, the service agent will converge it for you, so you won’t have to use this bit of information for a while.

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