NotTaR of Television Sets : Jittering or flickering due to problems ..  
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Jittering or flickering due to problems with AC power

If you have eliminated other possibilities such as electromagnetic interference from nearby equipment or a faulty video cable or problems with the video input (e.g., cable or VCR) - then noisy or fluctuating AC power may be a possibility. However, most modern TVs usually have well regulated power supplies so this is less common than it used to be. Then again, your TV may just be overly sensitive. It is also possible that some fault in its power supply regulator has resulted in it becoming more sensitive to small power fluctuations that are unavoidable.

One way to determine if the problem is likely to be related to AC power is to run the TV on clean power in the same location connected to the same video input. For example, running it on an Uninterruptible Power Source (UPS) with the line cord pulled from the wall socket would be an excellent test. The output of the UPS's inverter should be free of any power line noise. If the TV's image has now settled down:

  1. Large appliances like air conditioners, refrigerator, or washing machines on the same circuit might cause significant power dips and spikes as they cycle.

    Plugging a table lamp into the same outlet may permit you to see any obvious fluctuations in power. What else is on the same circuit? Depending on how your house or apartment is wired, the same feed from the service panel may be supplying power to widely separated areas.

  2. For some unfathomable reason, your TV may just be more sensitive to something about the power from the circuit in that room. There may be nothing actually wrong, just different. While unlikely, a light dimmer on the same circuit could be producing line-conducted interference.

    If you have a multimeter, you could at least compare the voltages between the location where it has problems and the one where it is happy. Perhaps, the TV is sensitive to being on a slightly different voltage. This might only be a problem if some circuitry in the the TV is marginal in some respect to begin with, however.

  3. There could be a bad connection somewhere on the circuit. If your house has aluminum wiring, this is a definite possibility.

    Try a table lamp since its brightness should fluctuate as well. This should be checked out by a competent electrician as it represents a real fire hazard.

An electrician may be able to pinpoint the cause but many do not have the training or experience to deal with problems of this sort. Certainly, if you find any power line fluctuations not accounted for by major appliances, on the same circuit this should be checked by an electrician.

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