Teac-EU-34-T-Service-Manual电路原理图.pdf

RadioFans.CN 收音机爱 好者资料库 TECHNICAL BULLETIN 10th Sep 1999 Page 1 of 1 MODEL: EU-34T (AK20 CHASSIS) PROBLEM: “White Dot Noise” pattern visible on low RF signal input. File: EU-34T (Whitedot).doc / EU-34T (Whitedot).pdf White dot noise pattern occurs when signal RF input is too low. This modification will improve the signal/noise vastly. Instructions: 1. Remove C820 (Ceramic Cap 270pF 1KV) 2. Insert (Ceramic Cap 470pF 1KV) into location C820 3. Add a 0.22nF 630V capacitor in parallel with D806. Regards, Fabian Lubanovic TEAC Australia Pty Ltd. RadioFans.CN 收音机爱 好者资料库 1 11AK20 CHASSIS CIRCUIT DESCRIPTION 1.GENERAL INFORMATION : This document provides detailed information about the fully I2C controlled Television Chassis named 11AK20. 11AK20 is based on the bus controlled circuits in which all the filters, traps and delay lines have been integrated. Therefore the numbers of external components are reduced and the user, service and factory adjustments are made through I2C BUS control. This chassis has been designed mainly for the 90?, 14? and 15? picture tubes. This chassis has a SMPS circuitry which has been designed to get low stand-by power consumption (less than 3W) as an option. On the other hand, it also has wide range (90-270V 50/60 Hz) mains as an option. The chassis covers almost all the existing worldwide transmission and colour standards as PAL B/G/I/M/N, SECAM B/G/D/K/K?/L/L? and NTSC M (3.58), NTSC (4.43) using same Main Printed Circuit Board by means of optional components and settings. Tuning system is Voltage Synthesized for all systems Except NTSC M and PAL M/N applications but it is Frequency Synthesized for NTSC M and PAL M/N applications. Furthermore, chassis has also European Wide-range teletext solution as an option. This solution supports all the European teletext standards optionally as 1 page normal, fast and top text modes. The chassis has Euro AV Plug (Scart Socket) for Peritel and SVHS connections. The pictures in 16 - 9 format can be displayed via this Peritel connection. Other optional external connections are front AV input RCA jacks, back AV output RCA jacks and Headphone jack. The software has been developed with a menu driven user interface supporting all possible chassis versions with a storage capacity of 100 programs. 2. IF STAGE : The inputs for IF stage are IF inputs from Tuner to produce front-end Video and Audio, Video and Audio from Scart or front AV RCA jack to be able to select the internal or external video and audio according to the control signals which comes from microcontroller and STV 2118. Then, the resultant video and audio signals are sent to video processing stage and audio output stage, respectively. Furthermore, front-end video and audio signals are sent to scart and or back AV RCA jacks. This part also produces some control signals for tuner and microcontroller. This stage was designed for processing positive (optional) and negative modulated mono and one scart applications. STV 8223 is the IF IC that is used in only negative modulation. There is an alignment which is the VCO adjustment (VL101). The procedure of alignment can be described briefly as follows : ?The IF signal is applied to the IF inputs in accordance with the standards (for B/G 38.9MHz) at pin # 1 and 2 of SAW filter (Z101). ?Adjust the VL101 until getting 2.5 V dc at pin # 9 of uC (IC501). This stage is also used for negative and positive modulated, mono applications. STV 8224 (negative and positive modulation and FM sound) (IC 101) and STV 8225 (AM sound) (IC102) are the IF IC?s. There are two alignments in this case, which are the VCO adjustment (VL101) for B/G - L standards and VC101 for L? standard. The procedure of the alignments can be described briefly as follows : The system is Switched to B/G standard reception, ?The IF signal is applied to the IF inputs in accordance with the standards (for B/G 38.9MHz) at pin # 1 and 2 of SAW Filter Z101. ?Adjust the VL101 until getting 2.5 V dc at pin # 9 of uC. ?The system is Switched to L? standard reception, ?The IF signal is applied to the IF inputs in accordance with the standards (for L? 33.9MHz) at pin # 1 and 2 of SAW Filter Z101. ?Adjust the VC101 until getting 2.5 V dc at pin # 9 of uC. 2.1 Video and Sound IF System one 112V output which is used for horizontal output and 33V generation needed by tuner section, one 16V output for all small signal sections an uC and one for audio output section. This chassis may be used in 90 - 270 volt with appropriate optional circuitry and components. The uC which is supplied by a source designed regulator with zener diode (D814) controls stand by mode by switching Q803 (for 44604 application Q806). 8. uC (MICROCONTROLLER) : The microcontroller hardware that is member of the ST6 family has a TV receiver control software with menu control. It controls the chassis through IIC bus, PWM outputs and I/O ports. Dominant features of controller are control of optional teletext, outputs for OSD, IR control signal receiving, and internal EEPROM. The controller has IIC communication port at # 40 , # 41 and OSD driver (R,G,B,FBl) at # 22, # 23, # 24, # 25. PWM control outputs are tuning # 34; vertical linearity adjustment # 1; AGC adjustment # 2. Other control outputs are Muting - video ident # 3; led driver # 4; system switches # 5, # 6, # 8, # 19, # 20, # 36; tuner switches # 18, # 19 and inputs are AFC information from IF # 9; keyboard # 10, # 11, # 13, # 14; scart mode ident (4/3-16-9) # 38, # 39; horizontal sync # 26; vertical # 27; infrared # 35 and reset # 33. The uC starts system according to option diodes configuration (D501, D503, D505, D506, D508). The controller has also a software which is able to control some service adjustments: R,G,B gain; R,G cut off; vertical position; vertical linearity; horizontal position; vertical amplitude; AGC; language selection for teletext. For enter to service mode followed procedure must be act within four seconds: 1-Press volume down button on the keyboard; 2-Press ?prog? button on the R/C hand set; 3-Press ?- -? button on the R/C hand set; 4-Press ?TV ? button on the R/C hand set; Parameters can be sellected by program up and down, parameter adjustments can be done by volume up and down buttons. Memorizing the adjusted parameters can be done by pressing red button. For exit from service mode Press ? TV ? button. 9. TELETEXT : The video signal coming from IF stage is fed to Data Slicer IC001. Then, there are two possibilities for decoding part; CF70095 or CF70195 for 1-Page simple text applications and CF7020X family for fastext and toptext applications. Finally, R, G, B and FBL signals are sent to the related inputs of STV2118. The alignment procedure for CF70095 or CF70195 application is as following: 1-Apply a video with teletext transmission and select for teletext. 2-Adjust the coil (VL001) for the voltage at pin # 28 2.5V. 10. CRT BASE-BOARD : When RGB signals enter the input of the video amplifier stage (CRT base-board), they are amplified by means of three symmetrical video amplifier stages. For this purpose three 2SC2482 high voltage, video output transistors are used. So, high gain-bandwidth product is achieved. Furthermore black level changes at the output amplifiers caused by temperature or component agings are compensated by means of a closed loop control system. For this reason the cathode current information (ICAT) is sent to STV2118. 6 %/27?(8527(;7 ?)25?81,7(;7 ?)25?(8527(;7 9$/,?)25?7(/(7(;7?237,21 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ,?it is usedas control and power ground. 5-Foldback InputThe foldback function provides overload protection. Feeding the foldback input with aportion of the VCC voltage (1.0V max) establishes on the system control loop a foldback characteristic allowing a smoother startup and sharper overload protection. Above 1.0V foldback input is inactive. 6-Overvoltage ProtectionWhen the overvoltage protection pin receives a voltage greater than 17V, the device is disabled and requires a complete restart sequence. The overvoltage level is programmable. 7-Current Sense InputA voltage proportional to the current flowing in to the power switch is connected to this input. The PWM latch uses this information to terminate the conduction of the output buffer when working in a corrent mode of operation. A maximum level of 1.0V allows either current or voltage mode of operation. 8-DemagnetizationA voltage delivered by an auxiliary transformer winding provides to the demagnetization pin an Detectionindication of the magnetization state of the flyback transformer. A zero voltage detection corresponds to complete core saturation. The demagnetization detection ensures a discontinuous mode of opertion. This function can be inhibited by connecting Pin 8 to Gnd. 9-Synchronization InputThe synchronization input pin can be activated with either a negative pulse going from a level between 0.7V and 3.7V to Gnd or a positive pulse going from a level between 0.7 and 3.7V up to a level higher than 3.7V. The oscillator runs free when Pin 9 is connected to Gnd. 10- CTThe normal mode oscillator frequency is programmed by the capacitor CT choice together with the Rref resistance value. CT, connected between Pin 10 and Gnd, generates the oscillator sawtooth. 11- Soft-Start/DmaxA capacitor, resistor or a voltage source connected to this pin limits The switching duty-cycle. /Voltage-ModeThis pin can be used as a voltage mode control input. By connecting Pin11 to Ground, the MC44603 can be shut down. 12- RP StandbyA voltage level applied to the RP Standby pin determines the output power level at which the oscillator will turn into the reduced frequency mode of operation (i.e. standby mode). An internal hysteresis comparator allows to return in the normal mode at a higher output power level. 13- E/A OutThe error amplifier output is made avaliable for loop compensation. 14- Voltage FeedbackThis is the inverting input of the Error Amplifier. It can be connected to the switching power supply output through an optical (or other) feedback loop. 15- RF StandbyThe reduced frequency or standby frequency programming is made by the RF Standby resistance choice. 16-RrefRref sets the internal reference current. The internal reference current ranges from 100?A to 500 ?A. This requires that 5.0kW < Rref < 25 kW. 8 ST 6385 8 BIT HCMOS MCUs FOR TV VOLTAGE SYNTHESIS WITH OSD GENERAL DESCIRIPTION The ST6385,86,87,88 microcontrollers are member of the 8-bit HCMOS ST638X family, a series of devices specially oriented to TV applications. Different pin-out and peripheral config?ration are avaiable to give the maximum aplication and cost flexibility. All ST638X members are based on a building block appoach: a common coreis surrounded by a combination of on-chip peripherals (macrocells) avaiable from a standard library. These peribherals are designed with the same Core technology providing full compatibility and short desing time. Many of these macrocells are specially dedicated to TV applications. The macrocells of the ST638X family are : two Timer peripherals each including an 8-bit counter with a 7 bit software programmable precaler (Timer), a digital hardware activated watchdog function (DHWD), a 14-bit voltage synthesis tuning pripheral, a serial peripheral interface (SPI), up to six 6-bit PWM D/A converters, an AFC A/D converter with 0.5V resolution, an on-screen display (OSD) with 15 characters per line, 128 characters (in two banks each of 64 chracaters). In addition the following memory resources are available: program ROM (20K), data RAM (256 bytes), EEPROM (384 bytes). Refer to pin configurations figures and to ST638X device summary (Table 1) for the definition of ST638X family members and a summary of differences among the different types. FEATURES n8-bit Architecture nHCMOS Technology n8Mhz Clock nUser Program ROM: 20140 bytes nReserved Test ROM: 336 bytes nData ROM: User selectable size nData RAM: 256 bytes nData EEPROM: 384 bytes n42-Pin Shrink Dual in Line Plastic Package nUp to 22 software programmable general purpose Inputs/Outputs,including 2 direct LED driving nOutputs nTwo Timers each including an 8-bit counter with a 7-bit programable prescaler nDigital Watchdog Fuction nSerial Peripheral Interface (SP) supporting S-BUS/ I2C BUS and standart serial protocols nUp to Six 6-Bit PWM D/A Converters n62.5KHz Output Pin (ST6386,88 Only) nAFC A/D converter with 0.5V resolution nFive interrupt vectors (IRIN/NMI, Timer 1 & 2, VSYNC, PWR INT.) n14 bit counter for voltage synthesis tuning nOn-chip clock oscillator n5 Lines by 15 Characters On-Screen Diplay Generator with 128 Characters nByte efficient instruction set nBit test and jump instructions nWait and Bit Manipulation insructions nTrue LIFO 6-level stack nAll ROM types are supported by pin-to-pin piggy-back versions. nThe develeopment tool of the ST638X microcon-trollers consists of the ST638X-EMU emulation and development system to be connected via a standard RS232 serial line to an MS-DOS Personal Computer. PINNING 1-DA0Output, Open-Drain, 12V 2-DA1Output, Open-Drain, 12V 3-DA2Output, Open-Drain, 12V 4-DA3Output, Open-Drain, 12V 5-DA4Output, Open-Drain, 12V 6-DA5Output, Open-Drain, 12V 7-62.5KHz OUTOutput, Open-Drain, 12V 8-AFCInput, High Impedance, 12V 9-VSOutput, Push-Pull 10- R,G,B, BLANKOutput, Push-Pull 11- HSYNC, VSYNCInput, Pull-up, Schmitt Trigger 12- OSDOSCINInput , High Impedance 13- OSDOSCOUTOutput, Push-Pull 14- TESTInput Pull-Down 15- OSCINInput, Resistive Bias, Schmitt Trigger to Reset Logic Only 16- OSCOUTOutput, Push-Pull 17- RESETInput, Pull-up, Schmitt Trigger Input 18- PA0I/O, Push-Pull, Software Input Pull-up, Schmitt Trigger Input 9 STV8224B MULTISTANDARD VIDEO AND SOUND IF SYSTEM WITH AUDIO AND VIDEO SWITCHES GENERAL DESCRIPTION The STV8224B is a picture and sound IF processor for multistandart application with very few external components and adjusments. It provides the audio and video switches for one SCART plug application. AM sound demodulation is perfomed with the STV8225 add-on. FEATURES : nV?deo PLL Demodulat?on nSound PLL Demodulat?on nPos?t?ve and Negat?ve Modulation nAGC for BG and L Standards nAud?o Sw?tch nDC Volume Control nV?deo Sw?tch PINNING 1-P?f PLL F?lter 2-AFC Output 3-CVBS Output 4-Sw?tching Input (Standard+INT/EXT) 5-IF LC 6-IF LC 7-Aud?o H?gh Pass F?lter 8-2nd IF Sound Input 9-Audio and ?nd IF Decoupl?ng 10- Internal V?deo Input 11- V?deo Sw?tch Output 12- External V?deo Input 13- Volume Control+mute 14- Aud?o Sw?tch Output 15- FM Demodulated Aud?o Output 16- External Aud?o Input 17- VCC 18- Grount 19- IF Input 20- IF Input 21- ACG Capac?tor (L Standard) 22- ACG Capac?tor 23- Tuner AGC Output 24- Tuner AGC start?ng po?nt Adjustment 19- PA1I/O, Push-Pull, Software Input Pull-up, Schmitt Trigge