NotTaR of Television Sets : Why do flyback (LOPT) transformers fail?
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Why do flyback (LOPT) transformers fail?

While flyback transformers can on occasion be blown due to a failure elsewhere in the TV or monitor's power supply or deflection circuits, in most cases, they simply expire on their own. Why?

Flybacks are wound with many layers of really really fine wire with really really thin insulation. This entire assembly is potted with an Epoxy resin which is poured in and allowed to cure.

In some ways, these are just short circuits waiting to happen.

Flybacks get hot during use and this leads to deterioration of the insulation. Any imperfections, nicks, scratches, etc. in the insulation contributes to failure. Temperature cycles and manufacturing defects result in fine cracks in the Epoxy potting material reducing the insulation breakdown particularly in the area of the high voltage windings, rectifiers, and focus/screen divider network.

It is amazing they last as long as they do with the stress they are under. They also physically vibrate to some extent. A whole bunch of other factors are also no doubt important.