Read Sharp 21LF-90H (serv.man3) Service Manual online
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AK - 44
CHASSIS
TABLE OF CONTENTS
SAFETY PRECAUTIONS ............................................................................................................................................... 5
TV set switched off ............................................................................................................................................... .....5
Measurements ....................................................................................................................................................... 5
Measurements ....................................................................................................................................................... 5
PERI-TV SOCKET ........................................................................................................................................................... 5
SCART 1........................................................................................................................................................................... 5
SCART 1........................................................................................................................................................................... 5
1. INTRODUCTION ......................................................................................................................................................... 6
CIRCUIT DESCRIPTIONS ............................................................................................................................................. 6
2. SMALL SIGNAL PART WITH STV2248 ..................................................................................................................... 6
2. SMALL SIGNAL PART WITH STV2248 ..................................................................................................................... 6
2.1 Vision IF amplifier ........................................................................................................................................... 6
2.2 QSS Sound circuit (QSS versions) ................................................................................................................. 6
2.3 AM Demodulator ........................................................................................................................................... 6
2.4 FM demodulator and audio amplifier (mono versions) .................................................................................. 6
2.5 Video switch ................................................................................................................................................... 6
2.6 Synchronisation circuit .........................................................................................................................................6
2.7 Chroma and luminance processing ................................................................................................................ 7
2.8 RGB output circuit .......................................................................................................................................... 7
2.9 µ-Controller .................................................................................................................................................... 8
2.2 QSS Sound circuit (QSS versions) ................................................................................................................. 6
2.3 AM Demodulator ........................................................................................................................................... 6
2.4 FM demodulator and audio amplifier (mono versions) .................................................................................. 6
2.5 Video switch ................................................................................................................................................... 6
2.6 Synchronisation circuit .........................................................................................................................................6
2.7 Chroma and luminance processing ................................................................................................................ 7
2.8 RGB output circuit .......................................................................................................................................... 7
2.9 µ-Controller .................................................................................................................................................... 8
2.9.1 Controls .............................................................................................................................................. 8
2.9 .2 Teletext ............................................................................................................................................. 8
2.9 .2 Teletext ............................................................................................................................................. 8
2.10 Video Path ..................................................................................................................................................... 9
2.11 Sound Path .................................................................................................................................................. 9
2.12 AV Input Signal Path ..................................................................................................................................... 9
2.11 Sound Path .................................................................................................................................................. 9
2.12 AV Input Signal Path ..................................................................................................................................... 9
2.12.1 Video and Sound ............................................................................................................................ 9
2.12.2 RGB ................................................................................................................................................ 9
2.12.2 RGB ................................................................................................................................................ 9
3. TUNER ....................................................................................................................................................................... 9
4. DIGITAL TV SOUND PROCESSOR MSP34X0 ........................................................................................................ 10
5. SOUND OUTPUT STAGE TDA7266L/TDA7266 ...................................................................................................... 10
6. VERTICAL OUTPUT STAGE WITH TDA8174A ....................................................................................................... 10
7. VIDEO OUTPUT AMPLIFIER TDA6107 ................................................................................................................... 11
8. POWER SUPPLY (SMPS) .......................................................................................................................................... 11
5. SOUND OUTPUT STAGE TDA7266L/TDA7266 ...................................................................................................... 10
6. VERTICAL OUTPUT STAGE WITH TDA8174A ....................................................................................................... 10
7. VIDEO OUTPUT AMPLIFIER TDA6107 ................................................................................................................... 11
8. POWER SUPPLY (SMPS) .......................................................................................................................................... 11
8.1 Start Up ......................................................................................................................................................... 11
8.2 Voltage Regulation .......................................................................................................................................... 11
8.3 Voltage Protection .......................................................................................................................................... 11
8.4 Current Regulation .......................................................................................................................................... 11
8.5 Standby operation .......................................................................................................................................... 12
8.6 Mode transition ............................................................................................................................................. 12
8.7 SMPS Switch Off .......................................................................................................................................... 12
8.2 Voltage Regulation .......................................................................................................................................... 11
8.3 Voltage Protection .......................................................................................................................................... 11
8.4 Current Regulation .......................................................................................................................................... 11
8.5 Standby operation .......................................................................................................................................... 12
8.6 Mode transition ............................................................................................................................................. 12
8.7 SMPS Switch Off .......................................................................................................................................... 12
9. LINE CIRCUIT ............................................................................................................................................................ 12
9.1 B.C.L. Circuit (Beam Current Limiter) ........................................................................................................... 13
10. SERIAL ACCESS CMOS 8K EEPROM 24C08 ...................................................................................................... 13
11. SAW FILTERS .......................................................................................................................................................... 13
11. SAW FILTERS .......................................................................................................................................................... 13
12. IC DESCRIPTIONS AND INTERNAL BLOCK DIAGRAM ..................................................................................... 13
ST92195 ................................................................................................................................................................ 14
STV224X ............................................................................................................................................................... 15
UV1315, UV1316, UV1336 .................................................................................................................................. 15
TDA7266/TDA7266L .......................................................................................................................................... 17
TDA8174 ..................................................................................................................................................................18
TDA6107 ................................................................................................................................................................ 18
MC44608 .................................................................................................................................................................19
MSP34X0G ..............................................................................................................................................................19
24C08 .................................................................................................................................................................... 20
STV224X ............................................................................................................................................................... 15
UV1315, UV1316, UV1336 .................................................................................................................................. 15
TDA7266/TDA7266L .......................................................................................................................................... 17
TDA8174 ..................................................................................................................................................................18
TDA6107 ................................................................................................................................................................ 18
MC44608 .................................................................................................................................................................19
MSP34X0G ..............................................................................................................................................................19
24C08 .................................................................................................................................................................... 20
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