MIVAR MOD.24 821 CHASSIS TV2368 - TV2371 INTERNAL VIEW.

 

 

  - The chassis is carrying all functions of the receiver and even the power supply.

- Chassis technology is mainly based on discretes but with further integration devices is replacing previous types completely based on discretes.

- Frame deflection output is based on TDA1170

Note the very large speaker.

TUNING / CONTROLS RT13-32   Remote Controlled Voltage Synthesizer (up to 32 stations) for TV.

The tuning control box is based around a SGS combination chipset:
M293B M104B AND A TDA4092 5 bit binary to 7-segment decoder driver (No external resistors are required if the LEDs are STANDARD CONFIGURATION FOR 2 DIGIT) 

ALL  MADE BY:

SGS is Società Generale Semiconduttori - Aquila Tubi E Semiconduttori (SGS-ATES, "Semiconductor General Society - Tubes and Semiconductors Aquila"), later SGS Microelettronica, a former Italian company now merged into STMicroelectronics
SGS Microelettronica and Thomson Semiconducteurs were both long-established semiconductor companies. SGS Microelettronica originated in 1972 from a previous merger of two companies:

• ATES (Aquila Tubi e Semiconduttori), a vacuum tube and semiconductor maker headquartered in the Abruzzese city of l'Aquila, who in 1961 changed its name into Azienda Tecnica ed Elettronica del Sud and relocated its manufacturing plant in the outskirts of the Sicilian city of Catania
• Società Generale Semiconduttori (founded in 1957 by Adriano Olivetti).

 SGS TDA4092

 ■ ROM MASK OPTION
■ STANDARD CONFIGURATION FOR 2 DIGIT 7-SEGMENT LED TO PRESENT THE NUMBERS 1 TO 32
■ CONSTANT CURRENT OUTPUT STAGES FOR DIRECT DRIVING OF COMMON ANODE  LEDs . OUTPUT PROVIDED TO DISPLAY THE STAND-BY MODE .

■ AV OUTPUT ACTIVATED WHENEVER PROGRAM 32 IS SELECTED
■ TTL COMPATIBLE INPUTS
■ 5 V SUPPLY VOLTAGE


DESCRIPTION
The TDA4092 is a monolithic integrated circuit de­ signed to display the program number (1 to 32) in TV or Radio sets in conjunction with voltage or fre­ quency synthesizers. The inputs accept a 5 bit bi­ nary code with TTL levels and have internal pull-up. The outputs can directly drive LED display elements with common anode. One ot these outputs is intended to display the stand-by mode of the set.


No external resistors are required if the LEDs are supplied at 5 V. The LEDs can also be supplied with higher voltage (up to 18 V) but in this case a single resistor in series with the LED elements must be used in order to limit the power dissipation of the IC ; moreover, a suitable Rext must be chosen. The circuit is produced in l2L technology and is available in a 24 pin dual in-line plastic package.


When operating with a supply voltage higher than 5.5 V for LED elements, It is necessary to limit the IC power dissipation by means of one external re­ sistance connected in series with the common point of the digits (R in fig. 2). Unused outputs must be connected to Vs taking into account the additional power dissipation. The value of R must be chosen taking into account the worst working conditions.

Power supply is realized with mains transformer and Linear transistorized power supply stabilizer, A DC power supply apparatus includes a rectifier circuit which rectifies an input commercial AC voltage. The rectifier output voltage is smoothed in a smoothing capacitor. Voltage stabilization is provided in the stabilizing circuits by the use of Zener diode circuits to provide biasing to control the collector-emitter paths of respective transistors.A linear regulator circuit according to an embodiment of the present invention has an input node receiving an unregulated voltage and an output node providing a regulated voltage. The linear regulator circuit includes a voltage regulator, a bias circuit, and a current control device.

In one embodiment, the current control device is implemented as an NPN bipolar junction transistor (BJT) having a collector electrode forming the input node of the linear regulator circuit, an emitter electrode coupled to the input of the voltage regulator, and a base electrode coupled to the second terminal of the bias circuit. A first capacitor may be coupled between the input and reference terminals of the voltage regulator and a second capacitor may be coupled between the output and reference terminals of the voltage regulator. The voltage regulator may be implemented as known to those skilled in the art, such as an LDO or non-LDO 3-terminal regulator or the like.
The bias circuit may include a bias device and a current source. The bias device has a first terminal coupled to the output terminal of the voltage regulator and a second terminal coupled to the control electrode of the current control device. The current source has an input coupled to the first current electrode of the current control device and an output coupled to the second terminal of the bias device. A capacitor may be coupled between the first and second terminals of the bias device.
In the bias device and current source embodiment, the bias device may be implemented as a Zener diode, one or more diodes coupled in series, at least one light emitting diode, or any other bias device which develops sufficient voltage while receiving current from the current source. The current source may be implemented with a PNP BJT having its collector electrode coupled to the second terminal of the bias device, at least one first resistor having a first end coupled to the emitter electrode of the PNP BJT and a second end, a Zener diode and a second resistor. The Zener diode has an anode coupled to the base electrode of the PNP BJT and a cathode coupled to the second end of the first resistor. The second resistor has a first end coupled to the anode of the Zener diode and a second end coupled to the reference terminal of the voltage regulator. A second Zener diode may be included having an anode coupled to the cathode of the first Zener diode and a cathode coupled to the first current electrode of the current control device.
A circuit is disclosed for improving operation of a linear regulator, having an input terminal, an output terminal, and a reference terminal. The circuit includes an input node, a transistor, a bias circuit, and first and second capacitors. The transistor has a first current electrode coupled to the input node, a second current electrode for coupling to the input terminal of the linear regulator, and a control electrode. The bias circuit has a first terminal for coupling to the output terminal of the linear regulator and a second terminal coupled to the control electrode of the transistor. The first capacitor is for coupling between the input and reference terminals of the linear regulator, and the second capacitor is for coupling between the output and reference terminals of the linear regulator. The bias circuit develops a voltage sufficient to drive the control terminal of the transistor and to operate the linear regulator. The bias circuit may be a battery, a bias device and a current source, a floating power supply, a charge pump, or any combination thereof. The transistor may be implemented as a BJT or FET or any other suitable current controlled device.

Power Supply: The examples chosen are taken from manufacturers' circuit diagrams and are usually simplified to emphasise the fundamental nature of the circuit. For each example the particular transistor properties that are exploited to achieve the desired performance are made clear. As a rough and ready classification the circuits are arranged in order of frequency: this part is devoted to circuits used at zero frequency, field frequency and audio frequencies. Series Regulator Circuit Portable television receivers are designed to operate from batteries (usually 12V car batteries) and from the a.c. mains. The receiver usually has an 11V supply line, and circuitry is required to ensure that the supply line is at this voltage whether the power source is a battery or the mains. The supply line also needs to have good regulation, i.e. a low output resistance, to ensure that the voltage remains constant in spite of variations in the mean current taken by some of the stages in the receiver. Fig. 1 shows a typical circuit of the power -supply arrangements. The mains transformer and bridge rectifier are designed to deliver about 16V. The battery can be assumed to give just over 12V. Both feed the regulator circuit Trl, Tr2, Tr3, which gives an 11V output and can be regarded as a three -stage direct -coupled amplifier. The first stage Tr 1 is required to give an output current proportional to the difference between two voltages, one being a constant voltage derived from the voltage reference diode D I (which is biased via R3 from the stabilised supply). The second voltage is obtained from a preset potential divider connected across the output of the unit, and is therefore a sample of the output voltage. In effect therefore Tr 1 compares the output voltage of the unit with a fixed voltage and gives an output current proportional to the difference between them. Clearly a field-effect transistor could do this, but the low input resistance of a bipolar transistor is no disadvantage and it can give a current output many times that of a field-effect transistor and is generally preferred therefore. The output current of the first stage is amplified by the two subsequent stages and then becomes the output current of the unit. Clearly therefore Tr2 and Tr3 should be current amplifiers and they normally take the form of emitter followers or common emitter stages (which have the same current gain). By adjusting the preset control we can alter the fraction of the output voltage' applied to the first stage and can thus set the output voltage of the unit at any desired value within a certain range. By making assumptions about the current gain of the transistors we can calculate the degree of regulation obtainable. For example, suppose the gain of Tr2 and Tr3 in cascade is 1,000, and that the current output demanded from the unit changes by 0.1A (for example due to the disconnection of part of the load). The corresponding change in Tr l's collector current is 0.1mA and, if the standing collector current of Tr 1 is 1mA, then its mutual conductance is approximately 4OmA/V and the base voltage must change by 2.5mV to bring about the required change in collector current. If the preset potential divider feeds one half of the output voltage to Tr l's base, then the change in output voltage must be 5mV. Thus an 0.1A change in output current brings about only 5mV change in output voltage: this represents an output resistance of only 0.0552.

THOMSON TDA3190 COMPLETE TV SOUND CHANNEL:

The TDA3190 is a monolithicintegratedcircuit in a
16-lead dual in-line plastic package.It performsall
the functionsneededfor the TV soundchannel :
.IF LIMITER AMPLIFIER
.ACTIVE LOW-PASSFILTER
.FM DETECTOR
.DC VOLUMECONTROL
.AF PREAMPLIFIER
.AF OUTPUT STAGE
DESCRIPTION
The TDA3190 can give an output power of 4.2 W
(d = 10 %) into a 16 Ω load at VS = 24 V, or 1.5 W
(d = 10 %) into an 8 Ω load at VS = 12 V. This
performance,togetherwiththe FM-IF sectionchar-
acteristicsof high sensitivity, highAM rejection and
low distortion, enables the device to be used in
almost every type of televisionreceivers.
The device has no irradiation problems, hence no
externalscreening is needed.
The TDA3190 is a pin to pin replacement of
TDA1190Z.
The electrical characteristics of the TDA3190 remain almost constant over the frequency range 4.5 to 6 MHz, therefore it can be used in all television standards (FM mod.). The TDA3190 has a high input impedance,so it can work with a ceramic filter or with a tuned circuit that provide the necessary input selectivity. The value of the resistors connected to pin 9, determine the AC gain of the audio frequency amplifier. This enables the desired gain to be selected in relation to the frequency deviation at which the output stage of the AF amplifier, must enter into clipping. Capacitor C8, connected between pins 10 and 11, determines the upper cutoff frequency of the audio bandwidth.To increase the bandwidth the values of C8 and C7 must be reduced, keeping the ratio C7/C8 as shown in the table of fig. 16. The capacitor connected between pin 16 and ground, together with the internal resistor of 10 KΩ forms the de-emphasis network. The Boucherot cell eliminates the high frequency oscillations caused by the inductive load and the wires connecting the loudspeaker.

TDA2541 IF AMPLIFIER WITH DEMODULATOR AND AFCDESCRIPTION
The TDA2540 and 2541 are IF amplifier and A.M.
demodulator circuits for colour and black and white
television receivers using PN P or NPN tuners. They
are intended for reception of negative or positive
modulation CCIR standard.
They incorporate the following functions : .Gain controlled amplifier .Synchronous demodulator .White spot inverter .Video preamplifier with noise protection .Switchable AFC .AGC with noise gating .Tuner AGC output (NPN tuner for 2540)-(PNP
tuner for 2541) .VCR switch for video output inhibition (VCR
play back).

 

 

 

 

  TDA1170 vertical deflection FRAME DEFLECTION INTEGRATED CIRCUIT
GENERAL DESCRIPTION f The TDA1170 and TDA1270 are monolithic integrated
circuits designed for use in TV vertical deflection systems. They are manufactured using
the Fairchild Planar* process.
Both devices are supplied in the 12-pin plastic power package with the heat sink fins bent
for insertion into the printed circuit board.
The TDA1170 is designed primarily for large and small screen black and white TV
receivers and industrial TV monitors. The TDA1270 is designed primarily for driving
complementary vertical deflection output stages in color TV receivers and industrial
monitors.
APPLICATION INFORMATION (TDA1170)
The vertical oscillator is directly synchronized by the sync pulses (positive or negative); therefore its free
running frequency must be lower than the sync frequency. The use of current feedback causes the yoke
current to be independent of yoke resistance variations due to thermal effects, Therefore no thermistor is
required in series with the yoke. The flyback generator applies a voltage, about twice the supply voltage, to
the yoke. This produces a short flyback time together with a high useful power to dissipated power
ratio.