دارات الخرج الأفقي الترانزستورية في الاجهزة الملونة .. كتاب التلفزيون الملون والعادي

11- 17 Horizontal transistor output circuits in colored devices:

Figure (17-20) shows a simplified schematic diagram of the horizontal output circuit of a 19-inch (48) cm (100 RCAXL) color TV.

circuit work:

The horizontal output transistor acts as a circuit breaker - it is either in the state of full connection (ON) or fully cut off (OFF), and the horizontal output transistor (401) is fed and powered by the regulated supply (110 volts). This voltage is also applied to the damping diode 403 CR - rectangular pulses of voltage (8) V are applied to the base from peak to peak (P-P), and the positive part of the pulse occupies 401 Q and connects it to ON at the end of 70% of the horizontal scan, and the coil 401 L is in a circuit The rule smoothes the wave.

When the transistor is connected to ON, it clears the line to about 70% of the end of the screen, and this happens because the current is now increasing in the deflection coils in the form of sawtooth

return line:

When the scan reaches the right end of the screen. The Q-401 transistor is switched to the OFF state, and the potential inductively in the output transformer and the deflection coils causes the circuit to vibrate at about (70 kHz). A voltage +B is also generated during the return time.

Damping process:

At the end of the first half of the cycle (70 kHz) of the induction oscillation. The voltage on the induction coils naturally reverses, and this causes the connection of a dual damping 403 CR, forming a low impedance load on the coils, and the oscillation is interrupted at the left end of the screen. The latent potential now causes current to pass through the deflection coils and the 403 CR's damping coupler and this insures about the first third of the scan. After the current passes through CR 401, it secures the remaining two-thirds of the scan line.

High Voltage Transformer Synthesis Circuit:

Returning to the previous diagram, we find that the tuning circuit (CI-L1) is connected in series with the high voltage transformer. This circuit is effective during the recoil time only, and it provides high voltage regulation.

Display control:

The capacitor C406 is tuned with deflection coils at the frequency of the feedback resonance - and the capacitor C407 can be shortened by a compass to adjust the width.

The Centring circuit

Many display valves can have a DC circuit. It is fed from the regulated feeding voltage - and the median current can be changed by connecting two serial resistances (R403 - R404) by means of (Jamper) links, and the third link is designated for not passing a continuous DC current in the deviation files - and the normal position of the link is on the right - where both resistances are in series.
The emergence of mediation:

​When the voltage on the deflection coils is s-shaped, it becomes less than 110 volts - and the 402 CR diode is connected. The median current passes through the deflection files. The way the current passes is as follows: From the supply voltage of 110 volts through the series resistance (one or two resistors) to the damping diode 402 CR. And in the deflection coils and the horizontal output transistor, which is in the conductive state

note :
​​​​​In the previous scheme, we find several coils on ferrite parts such as FB406 - FB405 - FB403 - FB401 - which are of low induction value. And it works like RF shockers - it writes transient high frequencies, and in some circuits these ferrite coils work to prevent jamming oscillations.

12-17 Pincushion deformation, horizontal (PIN):

This distortion is observed in large screens with a deviation greater than 110 - especially in the four edges of the screen. The reasons for this distortion have been explained in the chapter on vertical deviation. Especially the non-spherical surface of the screen relative to the center of the beam. Now we are satisfied with the correction circuits used in the horizontal stage. The correction of the deformation phenomenon of the pins unit (Fig. 17-20) is achieved in two stages

They :

1- Gradually increasing the horizontal width as the deviation advances from the top of the screen to its center.

2- Reducing the horizontal width gradually as the deviation progresses from the center of the screen to the bottom.

circuit work:

There are several circuits designed to correct the horizontal pincushion distortion. The circuit shown is one of these circuits.

The primary coil (V2) (V1) of the correction transformer (PIN) is fed from the vertical output transistor - while the secondary is connected in series with the deflection coils and the output transformer.

Modify stream deviation files:

​​​​​​The trapezoidal wave of the vertical frequency (50 Hz) appears through H2 - in the form of a parabola (17 - 22) and it works to modify the horizontal deviation current. The horizontal sweep current in Figure B is shown to be lowest at the top of the linear structure (the raster) and gradually increase to its greatest end, at the vertical center, and then even below the linear structure (the raster). Where it returns to its small end - and compared to the shape, the correction of the sweep current appears to have an opposite effect to the structure deformed by the phenomenon of pins from side to side only, and as a result, the horizontal sweep current makes the sides of the linear structure straight