Horizontal TV Receiver (HTVR)

Substance:

OSC. HOR. HARTLEY'S WORKING METHODS
OSC. HOR. COUNTN DOWN
Function and Work of HOR DRIVE Parts
Function and Operation of HOT Parts.
POWER TRANSISTORS
DAMPER DIODE
RESONANT CAPACITOR
FERITE CORE
HOR SCAN DEFECT CORRECTION.
HOW A HALF-WAVE TWO VOLTAGE FOLDING CIRCUITS WORKS

1. How OSC Works. HOR. Hartley

Hartley Model Horizontal Oscillator Circuit

The resonant frequency is determined by the value of the parallel circuit of the resonator L1. Transistor Q1 is used as an active amplifier and gets a bias voltage from R8. Capacitor C2 is used as a positive feedback couple so that the circuit can resonate the osc frequency. adjusted by adjusting the ferrite core of the inductor L1 to have a center tap, where the center tap towards GND has fewer turns than the one towards the capacitor (C2).

2. OSC. HOR. COUNTN DOWN

OSC circuit. Hor. Count Down

VCO uses external ceramic resonator to produce 500KHz (32FH) frequency from this frequency, which is done after going through driver (8) and (4), then HOR frequency will be obtained. (FH) so that HOR frequency is stable, then it is equipped with HOR circuit. AFC.

3. Function and Operation of HOR DRIVE Parts

Horizontal Driver Circuit

Functions as a power provider to control the HOT transistor so that it can saturate (on full phase).

In order to obtain maximum efficiency, the interstage couple uses a transformer as an impedance matching, the HOR.DRIVE output section has a high impedance and the HOR. transistor input section has a lower impedance, because the output load is in the form of a coil, when the transistor is "off", it will cause parasitic oscillations that occur due to resonance between the transformer primary coil and the floating capacitive of the circuit to eliminate this parasitic oscillation, a serial RC Filter is installed on the primary section of the HOR.DRIVE transformer.

The RC Decoupling Filter is installed on the supply section to eliminate the supply voltage ripple which can cause black and white vertical lines on the left side of the raster.

4. Function and Operation of the HOT Section.

The main function is to provide sawtooth current to control the deflection yoke HVT (High Voltage Tension) also functions as an output load for the HOT transistor. Generally used capacitive couple (with ELCO) to connect from HOR.OUT to the deflection yoke. The main components of the HOR.OUT circuit to the deflection yoke are as follows:

5. POWER TRANSISTORS

The transistor is HOT DRIVE by square pulses and acts as an on-off switch.

6. DAMPER DIODE

Generally, it is one unit with the HOT transistor, if the diode is open (damaged) it will cause ringing interference on the raster in the form of black and white HOR lines on the right side of the raster and if left on for too long it will cause TR.HOR to be damaged.

7. RESONANT CAPACITOR

Tr.HOT damper diode and resonant capacitor as a whole determine the shape of the sawtooth current, changes in the capacitor value will affect the width of the HOR deflection. (HOR.size), if the value of this capacitor decreases to a lot / is not installed, it will cause the TR.HOR out to be damaged.

8. FERITE CORE

In this section, a ferrite core is sometimes used on the legs of the transistor which functions to prevent the HOR frequency from being transmitted by the relevant section, because if it is received back by the tuner section, it can cause interference to the monitor.

9. CORRECTION OF SCAN HOR DEFECTS.

Functions to correct HOR deflection defects. In the HOR.OUT section, several types of corrector circuits can be found.

When Q1 is ON (Sw 1 is closed), electric current (L) flows through the power supply.
When Q501 is off (Sw1 is open) the electric current in the deflection yoke is not immediately zero, due to the natural properties of the coil through which the electric current passes, therefore the electric current LY charges the capacitor (C2).
When the C charge is complete, the capacitor (c) releases its contents (discharge) towards LY as I3.
When the discharge current I3 is finished, then a counter electromotive force (reverse electromotive force) arises in LY where it is forward biased towards the diode, thus flowing I4 through the diode, thus this event always repeats itself.

CRT anode voltage should be high approaching 25kv.
to produce high voltage it uses HOR output. and the image above is an example of a circuit with high voltage.
HOR output pulse. is given to the doubler rectifier circuit, usually the high voltage generator circuit is made together with the HOR output deflection circuit.
on TV with a large screen (inch) requires a larger output power from the HOR output transistor, then the HOR output transistors use a parallel circuit technique, or there are also those that use a high voltage generator circuit separately with the HOR deflection circuit.

10. How the Half Wave Voltage Bifolding Circuit Works

If E1 is given a voltage, then C3 gets a charge with the current direction shown as in (1), so that the voltage is the same as E1, then C3 gets another voltage from E2, so that the charge is drained with the current direction shown by (2) in the image.
This drain current is to provide a charge to the 2 capacitors C1 and C2, but because the voltage E2 is negative and the capacitors C1 and C2 are in series and charged by the summing circuit E1 and E2, the voltage on C1 and C2 has a value of (E1 + E2)/2
When E1 is on, C3 gets a charge through the path (current direction (3)) in Fig. because C1 and C2 have received a charge, the current path through D1, D2 and D3 is cut off by each of these capacitors.
The voltages of C1 and C2 are each (E1 + E2)/2 and the voltage on C3 = E1+(E1+E2)/2. Furthermore, if voltage E2 is given, the charge on C1 and C2 will have a value of (E1+E2).3/4, because the voltage on C1 and C2 is the sum of the voltage of E2 with the voltage on the charge of C3 as the result of the voltage loading to 2E1+E2=3E1, therefore this circuit is called a TRIPLER RECTIFIER circuit (1/2 wave tripler).
In a high voltage circuit that uses a pulse floating back to E1, much larger than E2, then the output of the circuit = DOUBLER RECTIFIER.

Netizens

Q1: BUDI 20 Apr 2016, 22:27:00 = super star.. the article is very complete, bro.

A1: Hello Mr. Budi, thank you and welcome to our site, hope it is useful and good luck.