Toshiba 29VH27E, Service Manual

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8.VIDEO OUTPUT AMPLIFIER TDA6109
The TDA6109 includes three video output amplifiers in order to drive the three cathodes of a colour
picture tube directly. To obtain maximum performance, the amplifier is used with black-current control.
9.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 135V for FBT input, +/-14V for audio amplifier, 8V 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 135V DC voltage, via an optocoupler (TCET 1102G) 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.
10.MICROCONTROLLER SDA5550
10.1.General Features
• Feature selection via special function register
• Simultaneous reception of TTX, VPS, PDC, and WSS (line 23)
• Supply Voltage 2.5 and 3.3 V
• ROM version is used.
10.2.External Crystal and Programmable Clock Speed
• Single external 6MHz crystal, all necessary clocks are generated internally
• CPU clock speed selectable via special function registers.
• Normal Mode 33.33 MHz CPU clock, Power Save mode 8.33 MHz
10.3.Microcontroller Features
• 8bit 8051 instruction set compatible CPU.
• 33.33-MHz internal clock (max.)
• 0.360 ms (min.) instruction cycle
• Two 16-bit timers
• Watchdog timer
• Capture compare timer for infrared remote control decoding
• Pulse width modulation unit (2 channels 14 bit, 6 channels 8 bit)
• ADC (4 channels, 8 bit)
• UART (rxd, txd)
10.4.Memory
• Up to 128 Kilobyte on Chip Program ROM
• Eight 16-bit data pointer registers (DPTR)
• 256-bytes on-chip Processor Internal RAM (IRAM)
• 128bytes extended stack memory.
• Display RAM and TXT/VPS/PDC/WSS-Acquisition-Buffer directly accessible via MOVX
• UP to 16KByte on Chip Extended RAM (XRAM) consisting of;
- 1 Kilobyte on-chip ACQ-buffer-RAM (access via MOVX)
- 1 Kilobyte on-chip extended-RAM (XRAM, access via MOVX) for user software
- 3 Kilobyte Display Memory
10.5.Display Features
• ROM Character set supports all East and West European Languages in single device
• Mosaic Graphic Character Set
• Parallel Display Attributes
• Single/Double Width/Height of Characters
• Variable Flash Rate
• Programmable Screen Size (25 Rows x 33...64 Columns)
• Flexible Character Matrixes (HxV) 12 x 9...16
• Up to 256 Dynamical Redefinable Characters in standard mode; 1024 Dynamical Redefinable
Characters in Enhanced Mode
• CLUT with up to 4096 colour combinations
• Up to 16 Colours per DRCS Character
• One out of 8 Colours for Foreground and Background Colours for 1-bit DRCS and ROM Characters