VESTEL 17MB15E-5, Service Manual

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10. POWER SUPPLY (SMPS)
The DC voltages required at various parts of the chassis are provided by an SMPS transformer controlled by the IC
MC44608, which is designed for driving, controlling and protecting switching transistor of SMPS. The transformer
generates 145V for FBT input, +/-14V for audio amplifier, 5V and 3.3V stand by voltage and 8V, 12V and 5V 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. This circuit produces a control voltage according to the changes in 145V DC voltage, via an
optocoupler (TCET1102G) to pin3 of the IC.
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.
11. MICROCONTROLLER
The Micronas SDA 55xx TV microcontroller is dedicated to 8 bit applications for TV control and provides dedicated
graphic features designed for modern low class to mid range TV sets. The SDA 55xx provides also an integrated
general purposefully 8051-compatible microcontroller with specific hardware features especially suitable in TV sets.
The microcontroller core has been enhanced to provide powerful features such as memory banking, data pointers and
additional interrupts, etc. The internal XRAM consists of up to 16 kBytes. The microcontroller provides an internal
ROM of up to 128 kBytes. ROMless versions can access up to 1 MByte of external RAM and ROM. The 8-bit
microcontroller runs at 33.33 MHz internal clock. SDA 55xx is realized in 0.25 micron technology with 2.5 V supply
voltage for the core and 3.3 V for the I/O port pins to make them TTL compatible. Based on the SDA 55xx
microcontroller the MINTS software package was developed and provides dedicated device drivers for many Micronas
video & audio products and includes a full blown TV control SW for the PEPER application chassis. The SDA 55xx is
also supported with powerful design tools like emulators from Hitex, Kleinhenz, iSystems, the Keil C51 Compiler and
TEDIpro OSD development SW by Tara Systems.
12. SERIAL ACCESS CMOS 4Kx8(32KBit)EEPROM 24C32A
The Microchip Technology Inc. 24AA32A/24LC32A(24XX32A*) is a 32 Kbit Electrically Erasable PROM. The device is
organized as four blocks of 8K x 8-bitmemory with a 2-wire serial interface. Low-voltage design permits operation
down to 1.8V, with standby and active currents of only 1µA and 1mA, respectively. It has been developed for
advanced, low-power applications such as personal communications or data acquisition. The 24XX32A also has a
page write capability for up to 32 bytes of data. Functional address lines allow up to eight devices on the same bus, for
up to 256Kbits address space.
13. 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.
14. 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