C21F65

21 (51cmV) NICAM STEREO TELEVISION
Our stylish television comes with Fastext, a NICAM stereo sound system, and a host of user friendly features.
q 21 (51cmV) NICAM Stereo Television q 50Hz q NICAM Stereo Sound q Fastext q 2 SCART Sockets q Front AV Sockets q 2 x 8W RMS Output q Light Silver Finish q Remote Control

Fastext

HITACHI DIGITAL MEDIA Hitachi Europe Ltd Whitebrook Park Lower Cookham Road Maidenhead Berkshire SL6 8YA Tel: 000 Fax: 500 www.hitachidigitalmedia.com
The specification above and photography is for reference only and may be subject to change.

SCART 2 (SC051) Audio right output Audio right input Audio left output Ground AF Ground Blue Audio left input Blue input AV switching input Ground Green Ground Red Ground Blanking Ground CVBS output Ground CVBS input CVBS output CVBS input Ground 0.5Vrms / 1K 0.5Vrms / 10K 0.5Vrms / 1K 0.5Vrms / 10K 0.7Vpp / 75ohm 0-12VDC /10K
1Vpp / 75ohm 1Vpp / 75ohm
This is a 90 chassis capable of driving 20/21 tubes at the appropriate currents. The chassis is capable of operating in PAL, SECAM and NTSC standards. The sound system is capable of giving 5 watts RMS output into a load of 8 ohms. One page, 7 page SIMPLETEXT, TOPTEXT, FASTTEXT and US Closed Caption is also provided. The chassis is equipped with a double-deck 42 pin Scart connector.

1. INTRODUCTION

2. SMALL SIGNAL PART WITH STV2248:
STV2248 video processor is essential for realizing all small signal functions for a color TV receiver. 2.1 Vision IF amplifier The vision IF amplifier can demodulate signals with positive and negative modulation. The PLL demodulator is completely alignment-free. Although the VCO (Toko-coil) of the PLL circuit is external, yet the frequency is fixed to the required value by the original manufacturer thus the Toko-coil does not need to be adjusted manually. The setting of the various frequencies (38.9 or 45.75MHz) can be made via changing the coil itself. 2.2 QSS Sound circuit (QSS versions) The sound IF amplifier is similar to the vision IF amplifier and has an external AGC de-coupling capacitor. The single reference QSS mixer is realised by a multiplier. In this multiplier the SIF signal is converted to the inter-carrier frequency by mixing it with the regenerated picture carrier from the VCO. The mixer output signal is supplied to the output via a high-pass filter for attenuation of the residual video signals. With this system a high performance hi-fi stereo sound processing can be achieved. The AM sound demodulator is realised by a multiplier. The modulated sound IF signal is multiplied in phase with the limited SIF signal. The demodulator output signal is supplied to the output via a low-pass filter for attenuation of the carrier harmonics. The AM signal is supplied to the output via the volume control. 2.3. AM DEMODULATOR The AM demodulated signal results from multiplying the input signal by itself, it is available on AM/FM output. 2.3 FM demodulator and audio amplifier (mono versions): The FM demodulator is realized as narrow-band PLL with external loop filter, which provides the necessary selectivity without using an external band-pass filter. To obtain a good selectivity a linear phase detector and constant input signal amplitude are required. For this reason the inter-carrier signal is internally supplied to the demodulator via a gain controlled amplifier and AGC circuit. The nominal frequency of the demodulator is tuned to the required frequency (4.5/ 5.5/6.0/6.5MHz) by means of a calibration circuit that uses the clock frequency of the -controller/Teletext decoder as a reference. The setting to the wanted frequency is realized by means of the software. It can be read whether the PLL frequency is inside or outside the window and whether the PLL is in lock or not. With this information it is possible to make an automatic search system for the incoming sound frequency. This is realized by means of a software loop that alternate the demodulator to various frequencies, then select the frequency on which a lock condition has been found. De-emphasis output signal amplitude is independent of the TV standard and has the same value for a frequency deviation of 25kHz at the 4.5MHz standard and for a deviation of 50kHz for the other standards. When the IF circuit is switched to positive modulation the internal signal on de-emphasis pin is automatically muted. The audio control circuit contains an audio switch and volume control. In the mono inter-carrier sound versions the Automatic Volume Leveling (AVL) function can be activated. The pin to which the external capacitor has to be connected depends on the IC version. For the 90 types the capacitor is connected to the EW output pin (pin 20). When the AVL is active it automatically stabilizes the audio output signal to a certain level. 2.4 Video switching The video processor (STV2248C) has three CVBS inputs and two RGB inputs. The first CVBS input is used for external CVBS from SCART 1, the second is used for either CVBS or Y/C from either SCART2 or BAV/FAV, and the third one is used for internal video. The selection between both external video inputs signals is realized by means of software and hardware switches. 2.5 Synchronization circuit The video processor (STV224X) performs the horizontal and vertical processing. The external horizontal deflection circuit is controlled via the Horizontal output pulse (HOUT). The vertical scanning is performed through an external ramp generator and a vertical power amplifier IC controlled by the Vertical output pulse (VOUT). The main components of the deflection circuit are: PLL1: the first phase locked loop that locks the internal line frequency reference on the CVBS input signal. It is composed of an integrated VCO (12MHz) that requires the chroma Reference frequency (4.43MHz or 3.58MHz crystal oscillator reference signal), a divider by 768, a line decoder, and a phase comparator. PLL2: The second phase locked loop that controls the phase of the horizontal output (Compensation of horizontal deflection transistor storage time variation). Also the horizontal position adjustment is also performed in PLL2. A vertical pulse extractor. A vertical countdown system to generate all vertical windows (vertical synchronization window, frame blanking pulses, 50/60Hz identification window.). Automatic identification of 50/60Hz scanning. PLL1 time constant control. Noise detector, video identification circuits, and horizontal coincidence detector. Vertical output stage including de-interlace function, vertical position control. Vertical amplitude control voltage output (combined with chroma reference output and Xtal 1 indication).

3. TUNER

Either a PLL or a VST tuner is used as a tuner. UV1316 (VHF/UHF) is used as a PLL tuner. For only PALM/N, NTSC M applications UV1336 is used as the PLL tuner. UV1315 (VHF/UHF) is used as a VST Tuner. Channel coverage of UV1316:

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(1). Enough margin is available to tune down to 45.25 MHz. (2). Enough margin is available to tune up to 863.25 MHz. Noise Low band Mid band High band Typical : 5dB : 5dB : 6dB Max. 9dB 9dB 9dB Gain All channels Gain Taper (of-air channels) Min. Typical Max. : 38dB 44dB 52dB : 8dB

Channel Coverage UV1336:

&+$11(/6 WR ' ( WR WR
Noise is typically 6dB for all channels. Gain is minimum 38dB and maximum 50dB for all channels. Channel Coverage of UV1315:
(1). Enough margin is available to tune down to 45.25 MHz. (2). Enough margin is available to tune up to 863.25 MHz. Noise Low band Mid band High band Typ. 6dB 6dB 6dB Max. 9dB 10dB 11dB Gain All Channels Gain Taper (off-air channels) Min. 38dB Typ. 44dB Max. 50dB 8dB
The MSP 34x0D is designed to perform demodulation of FM or AM-Mono TV sound. Alternatively, two-carrier FM systems according to the German or Korean terrestrial specs or the satellite specs can be processed with the MSP 34x0D. Digital demodulation and decoding of NICAM-coded TV stereo sound, is done only by the MSP 3410. The MSP 34x0D offers a powerful feature to calculate the carrier field strength which can be used for automatic standard detection (terrestrial) and search algorithms (satellite). 5. SOUND OUTPUT STAGE TDA7266L/TDA7266 TDA7266L is used as the AF output amplifier for mono applications. It is supplied by +12VDC coming from a separate winding in the SMPS transformer. An output power of 5.5W (THD=0.5%) can be delivered into an 8ohm load. TDA7266 is used as the AF output amplifier for stereo applications. It is supplied by +12VDC coming from a separate winding in the SMPS transformer. An output power of 2*5.5W (THD=0.5%) can be delivered into an 8ohm load.
4. DIGITAL TV SOUND PROCESSOR MSP34X0

MC44608

General description: The MC44608 is a high performance voltage-mode controller designed for offline converters. This high voltage circuit that integrates the startup current source and the oscillator capacitor, requires few external components while offering a high flexibility and reliability. The device also features a very high efficiency standby management consisting of an effective Pulsed Mode operation. This technique enables the reduction of the standby power consumption to approximately 1W while delivering 300mW in a 150W SMPS. Integrated startup current source Loss less offline startup Direct offline operation Fast startup General Features Flexibility Duty cycle control On chip oscillator switching frequency 40, or 75kHz Secondary control with few external components Protections Maximum duty cycle limitation Cycle by cycle current limitation Demagnetization (Zero current detection) protection Over V CC protection against open loop Programmable low inertia over voltage protection against open loop Internal thermal protection GreenLine Controller Pulsed mode techniques for a very high efficiency low power mode Lossless startup Low dV/dT for low EMI radiations
PINNING 1. Demagnetization 2. I Sense 3. Control Input 4. Ground 5. Driver 6. Supply voltage 7. No connection 8. Line Voltage
PIN VALUE Zero cross detection voltage : 50 mV typ. Over current protection voltage 1V typ. Min : 7.5V Max. : 18V Iout 2Ap-p during scan 1.2Ap-p during flyback Output resistor 8.5 Ohm sink 15 Ohm source typ. Max : 16V (Operating range 6.6V-13V) Min : 50V Max : 500V

MSP34X0D

The MSP 34x0D is designed to perform demodulation of FM or AM-Mono TV sound. Two kinds of MSPs are used. MSP 3400D and MSP3410D. The MSP 3400D is fully pin and software-compatible to the MSP3410D, but is not able to decode NICAM. It is also compatible to the MSP3400C. General description: Demodulator and NICAM Decoder Section The MSP34x0D is designed to perform demodulation of FM or AM-Mono TV sound. Alternatively, two-carrier FM systems according to the German or Korean terrestrial specs or the satellite specs can be processed with the MSP34x0D. Digital demodulation and decoding of NICAM-coded TV stereo sound, is done only by the MSP3410. The MSP34x0D offers a powerful feature to calculate the carrier field strength, which can be used for automatic standard detection (terrestrial) and search algorithms (satellite). General Features Two selectable analog inputs (TV and SAT-IF sources) Automatic Gain Control (AGC) for analog IF input. Input range: 0.103Vpp Integrated A/D converter for sound-IF inputs All demodulation and filtering is performed on chip and is individually programmable Easy realization of all digital NICAM standards (B/G, D/K, I & L) with MSP3410G. FM demodulation of all terrestrial standards (incl. identification decoding) FM demodulation of all satellite standards No external filter hardware is required Only one crystal clock (18.432MHz) is necessary FM carrier level calculation for automatic search algorithms and carrier mute function DSP Section (Audio Base band Processing) Flexible selection of audio sources to be processed Two digital input and one output interface via I2S bus for external DSP processors, featuring surround sound, ADR etc. Digital interface to process ADR (ASTRA Digital Radio) together with DRP3510A Performance of all de-emphasis systems including adaptive Wegener Panda 1 without external components or controlling Digitally performed FM identification decoding and de-matrixing Digital base-band processing: volume, bass, treble, 5-band equalizer, loudness, pseudo-stereo, and base-width enlargement Simple controlling of volume, bass, treble, equalizer etc. Analog Section four selectable analog pairs of audio base-band inputs (= four SCART inputs) input level : = < 2VRMS, input impedance : >= 25kW one analog mono input (i.e. AM sound): input level : = < 2VRMS , input impedance : > = 15kW two high-quality A/D converters, S/N-Ratio : > = 85dB 20Hz to 20kHz bandwidth for SCART-to-SCART copy facilities

General description: The 24C16 is a 8Kbit electrically erasable programmable memory (EEPROM), organized as 4 blocks of 256 * 08 bits. The memory operates with a power supply value as low as 2.5V. Features: Minimum 1 million ERASE/WRITE cycles with over 10 years data retention Single supply voltage: 4.5 to 5.5V Two wire serial interface, fully IC-bus compatible Byte and Multi-byte write (up to 8 bytes) Page write (up to 16 bytes) Byte, random and sequential read modes Self timed programming cycle
PINNING 1. Write protect enable 2. Not connected 3. Chip enable input 4. Ground 5. Serial data address input/output 6. Serial clock 7. Multibyte/Page write mode 8. Supply voltage
PIN VALUE : 0V : 0V : 0V : 0V : Input LOW voltage : Min : -0.3V, Max : 0.3*Vcc : Input HIGH voltage : Min : 0.7*Vcc, Max : Vcc+1 : Input LOW voltage : Min : -0.3V, Max : 0.3*Vcc : Input HIGH voltage : Min : 0.7*Vcc, Max : Vcc+1 : Input LOW voltage : Min : -0.3V, Max : 0.5V : Input HIGH voltage : Min : Vcc-0.5, Max : Vcc+1 : Min :2.5V, Max : 5.5V

TDA1308

Features: Wide temperature range Excellent power supply ripple rejection Low power consumption Short-circuit resistant High performance high signal-to-noise ratio low distortion PINNING 1. Output A (Voltage swing) 2. Inverting input A 3. Non-inverting input A 4. Ground 5. Non-inverting input B 6. Inverting input B 7. Output B (Voltage swing) 8. Positive supply Saw filters list: PIN VALUE : Min : 0.75V, Max : 4.25V : Vo(clip) : Min : 1400mVrms : 2.5V : 0V : 2.5V : Vo(clip) : Min : 1400mVrms : Min : 0.75V, Max : 4.25V : 5V, Min : 3.0V, Max : 7.0V

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PINNING 1. Input 2. Input-ground 3. Chip carrier-ground 4. Output 5. Output

K9656M, L9653M

PINNING 1. Input 2. Switching Input 3. Chip carrier-ground 4. Output 5. Output

CIRCUIT DESCIRIPTION

The ZX series of receivers incorporate a Motorola switch mode power supply using a MC44608 regulator controller IC. The circuit provides power to the receiver in both standby and normal operation modes. The switch on the mains supply is fed through the mains filter network TR801, the surge limiter resistor R828,the bridge rectifier diodes D811/13/37/38, and reservoir capacitor producing approx. 320volts D.C to feed the switching MOSFET Q801 via the primary winding of TR802 pins 6 and 7. Start up resistor R801 feeds from a 500V coming from the mains through the adder diodes D809, D890 to pin 8 of IC800, the IC uses 9mA current source and connects it internally to VCC at pin6 allowing a rapid charge enough for start up. Then IC800 responds with the oscillator starting to oscillate at a 40khz frequency fixed by the IC manufacturer. The IC then produces, pulse width modulation pulses, at this frequency on pin 5 to drive the base of the switching FET Q801, that will then switch current on and off through the primary of TR802, which will in turn provides voltages in the secondary windings. The secondary winding voltages being proportional to the length of time that Q801 is turned on in each cycle. The voltage produced between pins 4 and 3 of TR802 is rectified by D804 developing aprox. 12 volts on C810, which takes over from the start up resistor to supply pin 8 of IC800. The Demag pin at pin 1 offers 3 different functions: Zero voltage crossing detection (50mV), 24mA current detection and 120mA current detection. The 24mA level is used to detect the secondary reconfiguration status and the 120mA level to detect an Over Voltage status called Quick OVP. The VCC at pin 6 operates between 6.6V and 13V in normal operation, when this voltage exceeds 15V then the IC output is disabled.

POWER SUPPLY

START UP

VOLTAGE REGULATION

After initial start up the secondary voltages of TR802 are established. These voltages then need to be regulated to the required levels. In a switch mode power supply such as this, it is the ON time of the switching FET Q801 that determines the output voltages produced. To provide regulation of the supply there is a feedback loop via an adjustable zener IC118 and an OPTO- coupler connected to pin 3 of IC800. The reference voltage of IC118 is set to 2.5V to supply a B+ voltage of 115V. Any fluctuation at this pin will cause IC800 to compensate it either by increasing or decreasing the voltage at the secondary outputs. The MC44608 offers two OVP functions: 1- A fixed function that detects when V CC is higher than 15.4V 2- A programmable function that uses the demag pin. The current flowing into the demag pin is mirrored and compared to the reference current Iovp (120mA). Thus this OVP is quicker than normal number one as it directly sense the change in current rather than waiting for a specific voltage value, and is called QOVP. In both cases, once an OVP condition is detected, the output is latched off until a new circuit STARTUP. 3- A software controlled function acts on pin 52 of IC501. This pin monitors feedback from both 8V and 5V via D512, then compares these to a reference value Vref pre-set by the hardware through resistors R545, R546, R548. In normal mode operation 1.2V < Vref < 2.4V. Any voltage outside this window will cause the micro controller to force the TV to stand by mode by lowering the standby port. Refer to standby mode. To monitor the current drawn by the receiver the source of Q801 is returned to the bridge rectifier through a low value resistor R807. All the current drawn by the receiver will flow through that resistor each time Q801 conducts, this will produce a voltage across the resistors proportional to the current drawn by the receiver. This voltage is fed to pin 2 of IC800 via R806.When the receiver is working normally the voltage across R807 is only a fraction of a volt and is not large enough to have any effect on IC800. Under fault conditions, if the receiver draws excessive current the voltage across R807 will rise. This voltage is monitored by the current sense input pin 2. This Current Sense pin senses the voltage developed on the series resistor R806 inserted in the source of the power MOSFET. When I sense reaches 1V, the Driver output (pin 5) is disabled. This is known as the Over Current Protection function. A 200mA current source is flowing out of the pin 3 during the startup phase and during the switching phase in case of the Pulsed Mode of operation. A resistor can be inserted between the sense resistor and the pin 3, thus a programmable peak current detection can be performed during the SMPS standby mode. Remember that all the primary side components of the power supply shown to the left of TR8O2 on the diagram are live to earth. It is recommended that a mains isolation transformer is used when servicing the receiver. Many of the components in the power supply are safety critical. (R828, R809) is a surge-Iimiting resistor, limiting the surge through the degauss coils when the reservoir capacitor is empty. These are marked with an exclamation mark in a triangle on the circuit diagram. These components MUST be replaced only with parts of identical value and safety characteristics. For reliability, it is recommended that only genuine parts are used for service replacements. Always check the main supply voltage feeding the line output stage after replacing parts in the power supply or line output circuit. The correct voltage is important for safety and reliability, the correct voltage should be 115 V 2 V.

VOLTAGE PROTECTION

CURRENT PROTECTION

SAFETY PRECAUTIONS

When servicing note that the reservoir capacitor C809 can remain charged to high voltage for some time after the a.c. supply is removed. This can result in a shock hazard or damage to components whilst working on the receiver. Do not try to test Q801 base emitter junction if C809 is charged, your meter will turn on the transistor which will discharge the capacitor resulting in a collector emitter short circuit. Do not discharge C809 quickly with a screwdriver etc. The very high current produced can damage the internal connections of the capacitor causing failure at a later date. Remember when checking voltages to use a return path on the same side of TR802 for the Voltmeter earth to obtain the correct readings. As mentioned earlier the Startup Management of MC44608 is as follows: The Vi pin 8 of IC800 is directly connected to the HV DC rail Vin. This high voltage current source is internally connected to the VCC pin and thus issued to charge the VCC capacitor. The VCC capacitor charge period corresponds to the Startup phase. When the VCC voltage reaches 13V, the high voltage 9mA current source is disabled and the device starts working. The device enters into the switching phase. To help increase the application safety against high voltage spike on pin 8 a small wattage 1k_series resistor is inserted between the Vin rail and pin 8. After this start-up the IC can distinguish between the different modes of operation using the following technique: The LW latch is the memory of the working status at the end of every switching sequence. Two different cases must be considered for the logic at the termination of the SWITCHING PHASE: 1. No Over Current was observed 2. An Over Current was observed These two cases correspond to the two signals NOC in case of No Over Current and OC in case of Over Current. The effective working status at the end of the ON time memorized in LW corresponds to Q=1 for no over current, and Q=0 for over current. To enter the standby mode secondary side is reconfigured using D889 loop, this starts with the microprocessor s pin 47 becomes high; as the standby port becomes high Q503 conducts and Q802 becomes off then D889 conducts and the high voltage output value becomes lower than the NORMAL mode regulated value. The shunt regulator IC118 is fully OFF. In the SMPS standby mode all the SMPS outputs are lowered except for the low voltage output that supply the wakeup circuit located at the isolated side of the power supply. In that mode the secondary regulation is performed by the Zener diode (D801) connected in parallel to the TL431. The secondary reconfiguration status can be detected on the SMPS primary side by measuring the voltage level at pin4 of TR802. In the SMPS standby mode the 3 distinct phases are: The SWITCHING PHASE: Similar to the Overload mode. The current sense clamping level is reduced. When VCC crosses the current sense section, the C.S. clamping level depends on the power to be delivered to the load during the SMPS standby mode. Every switching sequence ON/OFF is terminated by an OC as long as the secondary Zener diode voltage has not been reached. When the Zener voltage is reached the ON cycle is terminated by a true PWM action. The proper SWITCHING PHASE termination must correspond to a NOC condition. The LW latch stores this NOC status. The LATCHED OFF PHASE: The MODE latch is set. The STARTUP PHASE is similar to the Overload Mode. The MODE latch remains in its set status (Q=1). The SWITCHING PHASE: The Standby signal is validated and the 200uA is sourced out of the Current Sense pin 2.

STANDBY OPERATION

MODE TRANSITION

SMPS SWITCH OFF

When the mains is switched OFF, so long as the electrolytic bulk capacitor provides energy to the SMPS the controller remains in the switching phase. Then the peak current reaches its maximum peak value, the switching frequency decreases and all the secondary voltages are reduced. The VCC voltage is also reduced. When VCC is less than 6,5V, the SMPS stops working. IC 501 controls all the functions of the receiver operated by the remote control and the front panel customer controls. It produces the on screen graphics, operates tuning, customers controls and engineering controls, and also incorporates all of the Teletext functions. It also controls the video processor, the audio processor, and the tuner. The circuits just mentioned are controlled via the IC bus. Also IC501 controls the video source switching, vertical position adjustment and the vertical linearity adjustment via its ports. An external 8K EEprom is used by the micro. The EEprom comes fully programmed. The main clock oscillator is 4.0MHz crystal X501 on pins 50 and 51. Reset is provided on pin 2 via Q504. On switching on pin 2 becomes high and the controller gets reset which stays valid till a low signal comes on that pin.

MICROPROCESSOR IC501

CONTROLS
Command information from the infra red remote controller is fed through the sensor IC502 to pin 1 of the microprocessor. Operation of the customer front panel keys is detected by pin 8 that is an ADC (analogue to digital converter). Pressing a switch will connect the 5V to the ground through a particular resistor that determines the value of the voltage on pin8 at that instant. This obtained value is comprehended by the micro and the corresponding operation is performed. Refer to the following table:

7VUUPI

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9 0(18
IC501 automatically switches from TV mode to AV1, AV2 by detecting the signal from pin 29 or pin 8 at the scart connector, through its 56, 55 pins. The picture mode is determined according to the following table:
9vrpyhtr WyhtrDprrvt Qvprqr

WR 9 WR 9 WR 9

79 PRGH PRGH PRGH
All the tuning functions are carried by the microprocessor IC501. Three tuning modes are available for this chassis, VST tuning, PLL tuning, and frequency tuning. In all of these both manual and automatic modes are possible. If Auto Tuning Mode is selected the receiver tunes Band1, Band2, and UHF, putting into memory the channel, signal strength (signals amplitude for VST and video indent for PLL), and tuning data of each TV station found. The memories are then stored automatically to put the channels into frequency order from lowest frequency to the highest one. In APS (Auto-Programming-System) TV sets the channels are stored according to the standard tables provided for each country. In VST mode IC501 generates the tuning control voltage as pulse width modulation output at pin 54. This pulse operates a voltage switch Q502 converting the 0 to 5V pulse into a 0 to 33V pulses that are then integrated and smoothed by R550/ 553/563 and C535/538/544 to give a steady DC voltage of value between 0 to 33V for tuning control on pin 2 of the tuner. IC501 also controls the band switching of the tuner by pins 12/13/14 via Q507, Q506 and Q505 for the different bands UHF, Band1, and Band2. In both PLL and frequency tuning modes the tuning process is controlled by IC501 via the IC BUS. In PLL mode a table for all the channels available is set according to the standards and the micro controller uses these values to set the central frequency of the required channel. This mode is quicker than VST mode. Frequency tuning is a new feature to this chassis, it takes the advantages of both VST and PLL tuning. As in PLL mode the tuning process is controlled via IC bus, however the channels are not predefined in the software by a table on the contrary these are scanned as in VST but here the frequency changes and not the voltage. In frequency tuning the micro generates IC signals to account for a 1Mhz frequency increment on the tuner and then scan all the frequency either manually or automatically. This method is faster than the VST and more precise than PLL tunings. Automatic fine tuning (AFT) correction voltage is done internally inside IC403 and fed to the microprocessor via IC BUS. This is used by the software to modify the mark space output at pin 54 producing the tuning voltage. The AFT voltage is also used in tuning mode to identify the presence of a signal whilst tuning. Tuner AGC voltage from pin 8 of IC403 is taken directly to the tuner. A pulse width modulation output is developed inside the processor and is fed to the audio processor in stereo sets and to the video processor in mono sets via the IC BUS to control the volume. The physical control on the front panel works in the same way. The microprocessor IC501 performs all of the teletext functions internally. The Composite Blanking video and Sync signal (CBVS) is input to pin 33 of the micro from pin 29 of IC403. When text is selected the text graphics are output as R.G.B signals on pins 15/16/17 of the micro and fed to pins 34/35/36 of IC403. At the same time pin 18 of the micro goes high taking pin 37 of IC403 high, blanking the picture and selecting text R.G.B. input. output, IC701. Note. mixed mode is available and fast text with 8 page memory. A.V SWITCHING A.V. input can be selected from the remote control or by applying 6 to12 volts from pin 8 of the scart connector, This takes pin 55/56 of the micro high (5 volts). When external A.V input is requested pin 55 or Pin 56 of the micro goes high. This is then transmitted via the IC bus to IC403, selecting external signals from the scart connector. SERVICE MODE The chassis incorporates an electronic service mode operated by the micro. Full details are given on pages 20 to 25 of the service manual. The mode is entered by a combination of button presses (4-7-2-5), whilst the Main menu is on the screen. You can select any adjustment and change it. A list of adjustments is available such as OSD position, IF central frequency adjustment, AGC, vertical linearity, size, position, horizontal position, R.G.B gains, APR, tuner settings for PLL tuners, and five options for the TV set features configurations.

FIELD OUTPUT VERTICAL SHIFT
A fly-back pulse is taken from pin 1 of the FBT transformer. This is required by IC403 (Pin 49) for burst / sync gating, and RGB line blanking. The ver_sync signal is output from the pin47 and fed to Pin 41 of IC501. The H_sync pulse is taken from pin 1 of the FBT and fed to the micro at pin 40.These two signals are required by the micro for graphics timing and also for text. IC403 generates a vertical pulse signal VER_OUT and V_AMP that are fed to IC600 (the vertical stage IC). IC600 is supplied by a 26V DC via diode D610.It generates its own ramp signal and based on the V_AMP & VER_OUT signals it produces the vertical deflection signals that are fed to connector PL601. Vertical linearity adjustment is controlled by Q604 which is driven by the PWM output of IC501 at pin 49. Vertical position adjustment is conducted by Q606 derived by the VER_OUT signal. Switching Q606 will change the DC voltage on VOUT_2 pin which will either lower or higher the picture. A DC level is supplied at VOUT_2 via D614 to stabilise the picture and make its position changeable.
B.C.L CIRCUIT (BEAM CURRENT LIMITER)
Beam current limiting is employed to protect the circuitry in the receiver, the CRT and to prevent excessive X Ray radiation in fault conditions. The current drawn by the CRT is monitored by the current drawn through the winding of the fly-back transformer that produces the EHT for the CRT anode. The end of the winding (Pin 10) is returned to IC403 Pins 46, the beam current drawn by the CRT passes through Q603 and develops a voltage on the collector proportional to the current (V=IxR). The voltage on the collector will vary depending on the beam current being drawn reducing the brightness and contrast of the picture. If the voltage is sufficiently negative (indicating very high excess beam current) the output will be reduced, reducing the picture brightness and contrast.
MANUAL ADJUSTMENT PROCEDURE
In order to enter service menu, first enter the main menu and then press the digits 4, 7, 2 and 5 respectively. To select adjust parameters, use $ or ' buttons. To change the selected parameter, use + or - buttons. Selected parameter will be highlighted. Entire service menu parameters are listed below. For some of parameters the default values are given on the same table.

REGISTER

OSD IF1 IF2 IF3 IF4 AGC VLIN VS1A VS1B VP1 HP1 VS2A VS2B VP2 HP2 RGBH WR WG WB BR BG APR FMP1 NIP1 SCP1 FMP2 NIP2 SCP2 F1H F1L F2H F2L BS1 BS2 BS3 CB OP1 OP2 OP3 OP4 OP5 TX1

PARAMETER

OSD Horizontal Position IF Coarse Adjust IF Fine Adjust IF Coarse Adjust for L-Prime IF Fine Adjust for L-Prime Automatic Gain Control Vertical Linearity Vertical Size for 50 Hz / 4:3 Vertical Size for 50 Hz / 16:9 Vertical Position for 50 Hz Horizontal Position for 50 Hz Vertical Size for 60 Hz / 4:3 Vertical Size for 60 Hz / 16:9 Vertical Position for 60 Hz Horizontal Position for 60 Hz RGB Horizontal Shift Offset White Point Adjust for RED White Point Adjust for GREEN White Point Adjust for BLUE Bias for RED Bias for GREEN APR Threshold FM Prescaler when AVL is OFF NICAM Prescaler when AVL is OFF SCART Prescaler when AVL is OFF FM Prescaler when AVL is ON NICAM Prescaler when AVL is ON SCART Prescaler when AVL is ON High Byte of crossover frequency for VHF1-VHF3 Low Byte of crossover frequency for VHF1-VHF3 High Byte of crossover frequency for VHF3-UHF Low Byte of crossover frequency for VHF3-UHF Band Switch Byte for VHF1 Meaningful for only Band Switch Byte for VHF3 Meaningful for only Band Switch Byte for UHF Meaningful for only Control Byte Meaningful for only PLL Tuner Option 1 (see the Option List) Option 2 (see the Option List) Option 3 (see the Option List) Option 4 (see the Option List) Option 5 (see the Option List) Teletext Option 1 (see the Option List)
NOTE (NUMBERS ARE DEFAULT VALUES FOR CONCERNED PARAMETER)
ADJUST HORIZONTAL POSITION FOR OSD 63 ADJUST VERTICAL LINEARITY ADJUST VERTICAL SIZE FOR 4:3 MODE (50 HZ) ADJUST VERTICAL SIZE FOR 16:9 MODE (50 HZ) ADJUST VERTICAL POSITION (50 HZ) ADJUST HORIZONTAL POSITION (50 HZ) ADJUST VERTICAL SIZE FOR 4:3 MODE (60 HZ) ADJUST VERTICAL SIZE FOR 16:9 MODE (60 HZ) ADJUST VERTICAL POSITION (60 HZ) ADJUST HORIZONTAL POSITION (60 HZ) CVBS RGB HORIZONTAL POSITION COMPENSATION 9 (STEREO ONLY) 20 (STEREO ONLY) 14 (STEREO ONLY) 18 (STEREO ONLY) 39 (STEREO ONLY) 14 (STEREO ONLY) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) MEANINGFUL FOR ONLY PLL TUNER (see tuner setting table) PERIPHERAL OPTIONS (see option table) RECEPTION STANDART OPTIONS (see option table) VIDEO OPTIONS (see option table) TV FEATURE OPTIONS (see option table) CHANNEL TABLE OPTIONS (see option table) TELETEXT OPTIONS (see option table)

USING COLOUR BUTTONS ON SERVICE MENU RED BUTTON (For Stereo models only): It switches the AVL to ON or OFF mode on service menu. AVL word is visible on service menu when AVL is on. GREEN BUTTON : It switched the PICTURE MODE to 4:3 or 16:9 on service menu. It is usefull when it is necessary to adjust 16:9 picture mode vertical size. YELLOW BUTTON : It switches to VERTICAL SCAN DISABLE mode. It is usefull to adjust screen voltage. BLUE BUTTON : It is used to adjust AGC and IF automatically on service menu. WHITE BALANCE ADJUSTMENT The following three parameters are used to make white balance adjustment. To do this, use a Colour Analyser. Using WR (White point adjust for RED), WG (White point adjust for GREEN), WB (White point adjust for BLUE) parameters, insert the + sign in the square which is in the middle of the screen. The suggested values for these parameters are given on the table above. AGC ADJUSTMENT In order to do AGC adjustment, enter a 60dBmV RF signal level from channel C-12 (224.25MHz) Select AGC parameter from service menu. Press BLUE (INSTALL) button from remote controller. The adjustment will be done automatically by software. See the AGC indicator on service menu, it must be 1. Check that picture is normal at 90dBmV signal level.

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IF NEGATIVE ADJUSTMENT (WITHOUT L SYSTEMS) Set the video pattern to a PAL colour bar pattern with frequency 38.9MHz. Apply this IF signal to PIN-10 and PIN-11 of tuner. Press PROG-1 and after that BLUE (INSTALL)button from remote controller. Select the standart as BG or I. (if BG is not available) Enter service menu. Select IF1 parameter from service menu and press BLUE (INSTALL) button from remote controller. IF adjustment will be done automatically by software. See the IF indicator on service menu, it must be like on FIGURE-1 shown above. IF POSITIVE ADJUSTMENT (WITH L SYSTEMS) Set the video pattern to a SECAM-L colour bar pattern with frequency 33.9MHz. Apply this IF signal to PIN-10 and PIN-11 of tuner. Press PROG-1 and after that BLUE (INSTALL)button from remote controller. Select the BAND VHF-1 (S1 S4 for PLL tuners) and standart as L. Enter service menu. Select IF1 parameter from service menu and press BLUE (INSTALL) button from remote controller. IF adjustment will be done automatically by software. See the IF indicator on service menu, it must be like on FIGURE-1 shown above. OSD HORIZONTAL POSITION ADJUSTMENT Select OSD parameter on service menu. Adjust the horizontal position of OSD to the middle of screen, by using the reference bar on bottom of service menu. TELETEXT BRIGHTNESS ADJUSTMENT Set the TV set to a channel with TeleText. Enter service menu. Press TEXT button from remote controller. Adjust BRIGHTNESS parameter to value 39 by using left-right buttons from remote controller. Press TV button and MENU button from remote controller respectively. Adjustment is done.

Vertical Linearity (VLIN) Enter a PAL B/G circle test pattern via RF. Change VLIN till you see circle as round as possible. Vertical Size (VS1A) Enter a PAL B/G circle test pattern via RF. Change VS1A (Vertical Size) till horizontal black lines on both the upper and lower part of the test pattern become very close to the upper and lower horizontal sides of picture tube and nearly about to disappear. Check and readjust Vertical Size item if the adjustment becomes improper after some other geometric adjustments are done. Vertical Size (VS1B) Enter a PAL B/G circle test pattern via RF. Enter Service Menu and press GREEN (PICTURE) button from remote controller to switch to 16:9 picture mode on Service Menu. Change VS1B (Vertical Size) till the picture becomes 16:9 format. Check and readjust Vertical Size item if the adjustment becomes improper after some other geometric adjustments are done. Vertical Position (VP1) Enter a PAL B/G circle test pattern via RF. Change Vertical Position till the test pattern is vertically centred. Horizontal line at the centre pattern is in equal distance both to upper and lower side of the picture tube. Check and readjust Vertical Position item if the adjustment becomes improper after some other geometric adjustments are done. Horizontal Position (HP1) Enter a PAL B/G circle test pattern via RF. Change Horizontal Position till the test pattern is Horizontally centred. Check and readjust Horizontal Position item if the adjustment becomes improper after some other geometric adjustments are done. Vertical Size (VS2A) Enter a NTSC-M circle test pattern via RF or video inputs. Change Vertical Size till the checkered parts of test pattern on both of upper and lower side disappear. Check and readjust Vertical Size item if the adjustment becomes improper after some other geometric adjustments are done. Vertical Size (VS2B) Enter a NTSC-M circle test pattern via RF or video inputs. Enter Service Menu and press GREEN (PICTURE) button from remote controller to switch to 16:9 picture mode on Service Menu. Change VS2B (Vertical Size) till the picture becomes 16:9 format. Check and readjust Vertical Size item if the adjustment becomes improper after some other geometric adjustments are done. Vertical Position (VP2) Enter a NTSC-M circle test pattern via RF or video inputs. Change Vertical Position till the test pattern is vertically centred. Horizontal line at the centre pattern is in equal distance both to upper and lower side of the picture tube. Check and readjust Vertical Position item if the adjustment becomes improper after some other geometric adjustments are done. Horizontal Position (HP2) Enter a NTSC-M circle test pattern via RF or video inputs. Change Horizontal Position till the test pattern is Horizontally centred. Check and readjust Vertical Size item if the adjustment becomes improper after some other geometric adjustmentsare done. RGB MODE Horizontal Position (RGBH) Enter a RGB circle test pattern via video inputs. Force the TV to RGB mode by pressing AV button from remote controller. Change RGB Horizontal Position till the picture is horizontally centred. Check and readjust RGBH item if the adjustment becomes improper after some other geometric adjustments are done.

50Hz. 4:3 Geometry Adjustment

60Hz Adjustments

50Hz Adjustments
60Hz. 4:3 Geometry Adjustment
50Hz. 16:9 Geometry Adjustment
60Hz. 16:9 Geometry Adjustment

OPTION SETTINGS

Select concerned OPTION from service menu. To change a bit on selected option press the same number from remote controller. So this bit will be changed from 1 to 0 or from 0 to 1. If any option is selected on service menu you will see an indicator row shows you the bit numbers.
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