In your TV the vertical oscillator runs free and automatically. That’s not good enough. For unless your vertical oscillator draws the beam down at precisely the exact time as the camera is doing so at the TV station, your TV picture wiroll. So, at the end of every second picture, the studio inserts a vertical locking or sync pulse into the video voltage. This transmitted vertical pulse, upon arrival at your TV is separated from the composite TV signal and sent to the vertical oscillator. At precisely the end of the picture information it is applied, and locks the vertical sweep into step, preventing flopover.
The horizontal sync works in a similar fashion. In order for you to see a picture and not a screenful of horizontal lines, the 525 lines must be drawn and whipped back precisely in time with the picture being scanned at the studio. So, at the end of every line of video information a horizontal sync pulse is placed into the video voltage. This pulse gets into your TV, is separated from the video and is presented to the hori-
The audio signal in contrast, modulates frequency of the carrier, that Is, the distance between the hills. zontal oscillator at precisely the end of each line of video. The pulse makes the oscillator fire precisely when it should and the yoke whips the electron beam back for the next line to begin.
This is the way all passengers, picture, sync and sound, are loaded into the carrier and radiated from the transmitting antenna. Your TV antenna absorbs some of the radiation and funnels it down to your set.
The Infallible “Aerial or Tuner?” Test: The first circuitry the loaded carrier runs into as it leaves your antenna system is the front end or tuner of your TV. Subsequently, antenna troubles and tuner troubles cause similar symptoms of trouble. This can cause you to &troubleshoot the antenna system when actually you have tuner trouble or vice versa.
If you have any of the prescribed symptoms there is a test you can perform to steer you correctly.
Disconnect the antenna wire from the antenna terminals and short the leads protruding from the antenna wire together. Sometimes aerial trouble will radiate into the TV even if the aerial is not connected to the TV. With the wires shorted this possibility is reduced. Attach a substitute indoor antenna onto the TV terminals. Examine the picture you receive with the substitute antenna.
If your trouble ceases at this point and you receive the normal reception you usually get with this substitute antenna, chances are the trouble is in your original, now disconnected, antenna. However, should the trouble remain even with the substitute aerial, chances are good you have tuner trouble rather than antenna problems.