All Things Vertical

The vertical deflection circuit has a vertical oscillator that is locked to the video signal by the vertical sync pulse taken from the sync separator. If you get a set that is rolling, somewhere the vertical oscillator has lost the sync pulse, or there is a problem in the vertical oscillator circuit.

A vertical drive circuit is then amplified and is inserted to the vertical output device in the TV set. In almost all sets today, the vertical output circuit is built into what is known as the vertical output IC. The vertical output pulse is then inserted in to the vertical winding after it goes through a coupling circuit, and the deflection yolk will scan the electron beam inside the picture tube 60 times a second up and down the screen surface. With the horizontal and the vertical pulling on the beam, it spreads out to make the picture.

The vertical output IC will have several legs or connections to shape the vertical pulse to be amplified by the vertical outputs by means of capacitors and resistors. In addition, the B+ and the B- are connected to these leads. On a lot of TV sets where the vertical may look squashed or lines in the top or bottom or simply not enough of vertical deflection, it is mostly these small inexpensive parts.

The vertical output IC is almost all the time connected to a metal heat sink. If you ever think you need to change an IC on a heat sink, be sure to apply some heat sink compound on the back of the new device.

In many older sets, as well as some of the newer ones, you will hear a steady buzzing when the set is on. This buzzing sound seems to change with scene

changes. This is the vertical windings of the TV set vibrating at 60 cycles per second when they get loose, and they start to make noise since 60 cycles per second is in the human hearing range. There's not really a lot you can do to stop this noise 100% besides changing out the deflection yolk. There are some old tricks, like sticking Popsicle sticks under the yolk windings, but I have seen tech’s crack the neck of the picture tube while doing this.

Conclusion

In closing of part one of this article, I want to stress that you can turn an easy repair into a expensive repair with the wrong solder or soldering equipment, or by playing with service menus, not knowing what does what, or by turning the controls inside a TV set just to see what will happen.

Many problems have simple solutions. It may just be a bad connection or blown fuse. If you ever have any doubts or do not feel comfortable with a repair or adjustment, let a professional do the repair or internal adjustments for you.

The next series will explain the degaussing circuit (and some tips on the subject), as well as the tuner circuits, IF circuits, audio output circuits, color circuits, video drivers, and the system controller circuits. Stay tuned!

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More Circuits of the Basic TV Set and What They Do: Part 1 | Part 2

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