NotTaR of Television Sets : About the vertical scan rate            
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About the vertical scan rate

Some people believe that the TV scan rate is locked to the local power line. TVs never ever used the line frequency for vertical rate. The vertical rate is not even equal to line frequency, actually 59.94 Hz (NTSC). It was set originally to 60 Hz to minimize the visibility of interference between the deflection and power transformer. When NTSC added color, it changed to 59.94 Hz for highly technical reasons. And, TVs no longer have power transformers.

See Symptoms of Some Common Deflection Problems when referring to the specific descriptions below.