Caple C702G Manual de Serviço descarregar pdf (Página 186)

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2) PURITY CORRECTION PART

2-A) NORTH/SOUTH purity correction

MPU controls output voltage by comparing the sensor voltage (IC801 pin48) with the reference voltage

(IC801 pin49) and GLOBALSYNC OSD.

The D/A converter (IC532 pin16) output center voltage is 2.5V and variable range is between 0V and +5V.

The DC output current flows in the EMF (Earth Magnetic Field) coil.

This current flows to the feedback resistor (R4J6) of IC4J1.

This current is detected as voltage at the feedback resistor.

NOTE) : During DEGAUSS, becomes Low level(D/A converter output voltage is 2.5V), therefore the current

doesn’t flow in the EMF coil.

And it prevents magnetization in the CRT.

(The example of image: Correction of NORTH/SOUTH purity)

2-B) Four corner purity correction.

MPU controls output voltage by comparing 4 input voltages(IC801 pin47,pin49,pin50,pin51) and

GLOBALSYNC (TOP LEFT, TOP RIGHT, BOTTOM LEFT, BOTTOM RIGHT) OSD.

The D/A converter IC532 (pin14:TOP LEFT, pin8:TOP RIGHT, pin9:BOTTOM LEFT, pin7:BOTTOM

RIGHT) output center voltage is 2.5V and variable range is between 0V and +5V.

The DC output current flows in the corner coil(four corner).

This current flows to the feedback resistor(R4N6,R4R6,R4L6,R4M6) of output circuit.

This current is detected as voltage at the feedback resistor.

NOTE) :During DEGAUSS, becomes Low level(D/A converter output voltage is 2.5V), therefore the current

doesn’t flow in the corner coil.

And it prevents magnetization in the CRT.

CRT face

EMF coil

Corner coil

TOP

LEFT

TOP

RIGHT

BOTTOM LEFT

BOTTOM RIGHT

CRT face

(

The exam

le of ima

e: Correction of four corner

urit

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Caple C702G Manual de Serviço Página 186