Toshiba 27WLT56B, Service Manual

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27” TFT TV Service Manual 05/09/2005
7. MAIN POWER SUPPLY (SMPS) AND POWER INTERFACE BOARD
The DC voltages required at various parts of the chassis and inverters are provided by an main power
supply unit and power interface board. The main power supply unit is designed for 24V and 12V DC
supply. Power interface board gen12V for audio amplifier, 5V and 3.3V stand by voltage and
8V, 12V, 5V and 3V3 supplies for other different parts of the chassis.
An optocoupler is used to control the regulation of line voltage and stand-by power consumption. There
is a regulation circuit in secondary side. During the switch on period of the transistor, energy is stored in
the transformer. During the switch off period energy is fed to the load via secondary winding. By varying
switch-on time of the power transistor, it controls each portion of energy transferred to the second side
such that the output voltage remains nearly independent of load variations.
8. MICROCONTROLLER
The microprocessor is embedded inside PW181 chip which also handles scaling, frame rate conversion
and OSD generation. The on-chip 16-bit microprocessor is a Turbo x86-compatible processor core with
on-chip peripherals (timers, interrupt controller, 2-wire serial master/slave interface, UART, I/O ports,
and more). Special peripherals such as Infrared (IR) pulse decoders and a digital pulse width modulator
(PWM) are also included. There are two independent 2-wire serial master/slave interface modules that
can be multiplexed to control up to five 2-wire serial ports. The slave 2-wire interface is designed for
HDCP use only (and requires the use of HDCP Image Processors). On-chip RAM of up to 64 Kbytes is
available. A complete microprocessor system can be implemented simply by adding external ROM. The
on-chip processor can be disabled to allow external processor control of all internal functions.
9. SERIAL ACCESS CMOS 4K x 8 (32K bit) EEPROM 24C32A
The Microchip Technology Inc. 24C32A is a 4K x 8 (32K bit) Serial Electrically Erasable PROM. It has
been developed for advanced, low power applications such as personal communications or data
acquisition. The 24C32A also has a page-write capability of up to 32 bytes of data. The 24C32A is
capable of both random and sequential reads up to the 32K boundary. Functional address lines allow
up to eight 24C32A devices on the same bus, for up to 256K bits address space. Advanced CMOS
technology and broad voltage range make this device ideal for low-power/low-voltage, non-volatile code
and data applications.
10. CLASS AB STEREO HEADPHONE DRIVER TDA1308
The TDA1308 is an integrated class AB stereo headphone driver contained in a DIP8 plastic package.
The device is fabricated in a 1 mm CMOS process and has been primarily developed for portable digital
audio applications.
11. SAW FILTERS
K9656M:
Standard:
• B/G
• D/K
• I
• L/L’
Features
• TV IF audio filter with two channels
• Channel 1 (L’) with one pass band for sound carriers at 40,40 MHz (L’) and 39,75 MHz (L’- NICAM)
• Channel 2 (B/G,D/K,L,I) with one pass band for sound carriers between 32,35 MHz and 33,40 MHz
Terminals
• Tinned CuFe alloy
Pin configuration
1 Input
2 Switching input
3 Chip carrier - ground
4 Output
5 Output