Question about Televison & Video
This can be coming from any of the components that use windings, such as inductors. These are generally located in the power supply and in the case where display tubes are used, these would be in the scan amplifier sections.
In the case of a projection and regular CRT type TV, there will be deflection yokes for the tube(s), and there will be induction coils used in the scan amplifiers.
As the coils age, their internal windings, especially on the outer layers may loosen up a little. Sometimes in the coil's construction there may be some resonance with the core of the coil if the core is a metal type. Sometimes if any of the bypass or decoupler capacitors start to go open with age, and the capacitors are used for noise suppression for an induction coil, the coil may start to make some audible noise.
If some outer windings of induction coils are getting a little loose this is generaly not serious. If there are capacitors going off value, this can lead to problems.
With these induction coils, depending on the layout design and the overall component design, there may be some audible noise generation from the coils.
The coils are reactive devices. They work with electro-magnetic fields between the windings, and in conjunction with their core if they are using a metalized core. When these coils operate in their related circuits, there are generally some type of electrical signal or modulation being applied through them. Normally these frequencies are outside of the audible spectrum. Because of sub-harmonics that can be generated it is possible that you may hear some resonance.
There are also other mechanical factors involved in dealing with any metal shielding in close proximity of any coils that are being driven. The high frequency magnetic fields can react with nearby metal shielding, and thus the shielding acts like an acoustic resonator for the coil.
Someone who is very familiar with this type of noise problem can service this. It can be a very time consuming job if there are modifications and mechancal fixes that have to be done. It is important to first determine that there are no faulty components in the first place that are contributing to the noise generation. With most TV sets, as they age the problem may become worse.
Posted on Sep 27, 2008
I would need the model number in order to help you. Please respond to this same post with the model number and I will try to assist you.
Posted on Sep 27, 2008
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Posted on Jan 02, 2017
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