Daewoo DTL- 25G6F, Руководство по обслуживанию

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The supply voltage for the TDA8351 is 16V at pin 3.
The flyback generator has a separate supply voltage of 45V on pin 6.
Horizontal deflection
The circuit contains horizontal drive, line output transformer.
The horizontal driver pulses from the TDA8844 are amplified in the horizontal drive circuit, to get sufficient base-drive
current for the high voltage switching transistor Q401.
During the horizontal scan period( =52 ) Q401 will conduct, and a sawtooth current flows from +132V through the
primary winding of the FBT to ground.
After this time Q401 is switched off and the energy stored in the FBT during the scan period will be transformed to the
flyback capacitor CT.
This energy transfer will take place in a cosine shape because the primary of the FBT and CT from a resonant circuit.
The time the energy is transferred from FBT to CT. and back to the FBT, is called the flyback time and will take place
in about 12
The flyback peak voltage is about 9 times the scan voltage.
In series with the horizontal deflection coil there is a (damped) linearity corrector coil.
During the scan there is some loss in the resistance of the deflection coil.
In the first part of a line the linearity corrector stores some energy in a permanent magnet until it is saturated.
This improves the linearity of the horizontal scan speed.
The required S correction for the picture tube can be adjusted with the value of C408.
The beam current limiting information (BeamCurr) is derived from the foot of the H.V winding of the FBT.
This is connected via resistor to +8V.
As the beam current increase, the voltage on line BeamCurr decreases.
Beam current is damped by a integration filter before it is fed back to TDA8844 pin 22.
The TDA8844 will decrease the contrast (and eventually the brightness) to limit the average beam current.
EW drive
The DC voltage on pin 45 is determined by the East-West driver stage input and may range from 1 to 8 volts.
To prevent distortion, the voltage must always be >1volt.
Because the DC voltage on pin 45 is equal to the minimal output voltage of the East-West driver stage (reached for i
ew
=
0), it is recommended to choose this level close to 1 volt for maximum range.
Video amplifiers
Three TDA6106Q integrated video amplifiers drive cathode of the picture tube directly.
They are protected against CRT flashover discharges and ESD (electro static discharge).
The three video amplifiers, have a beam current output I black, used by the TDA8844 black current loop to control
the black level on the cathodes.
The outputs can be connected together because the black current 100p sequentially controls the black level for each
cathode.
The amplification of the TDA6106Q is set by the resistors between pin 3 and 9 and between pin 3 (negative-input) and
the TDA8844 output.
There are no alignment any more on the CPT panel, because of the automatic black current stabilization and because
the white point adjustment can be done in the TDA8844 via I2C bus.
.