Daewoo DDT-21H9ZZF, Service Manual

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Service Manual CP-099F
5-8-3 Guard circuit
The guard signal is not used.
5-8-4 Damping resistor
For HF loop stability a damping resistor (R313,R315) is connected across the deflection coil.
5-8-5 EAST-WEST Amplifier (TDA8358J)
The East-West amplifier is current driven. It can only sink currents of the diode modulator circuit. A feedback resistor
R305 is connected between the input and output of this inverting amplifier in order to convert the East-West correction
input into an output voltage.
5-9 Power supply (STR F6654)
5-9-1 STR-F6654 general description
The STR-F6654 is an hybrid IC with a build-in MOSFET and control IC, designed for flyback converter type switch
mode power supply applications.
5-9-2 Power supply primary part operations
An oscillator generates pulses signals which turn on and off a MOSFET transistor.
5-9-2-1 Start-up circuit : V
IN
The start-up circuit is used to start and stop the operation of the control IC, by detecting a voltage appearing at V
IN
pin (pin 4).
SMPS TRANS
R809
D812
L803
C807
3 4 7 6
Drain
C810
R806
D807
D806
C808
C809
D808
D809
Main AC voltage
Vin
STR-F6654
Ground
3
5
4
Fig : Power supply start-up circuit
When the power switch is pushed on, V
IN
increases slowly. During this time, C810 is charged through R806.
As soon as V
IN
reaches 16V, the STR-F6654 control circuit starts operating. Then, V
IN
is obtained by smoothing the
winding voltage which appears between pin6 and pin7 of the SMPS transformer.