Acer AC511 SERIES Servicehandleiding - Pagina 11

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5-2 DEFLECTION CIRCUIT

The deflection circuit is achieved by a high performance and efficient solution IC 401 (TDA9115) for this

monitor. The concept is fully DC controllable and can be used in applications with a micro-controller solutions.

The TDA9115 provides sync. Processing with full auto sync. Capability, a flexible SMPS block and an extensive

set of geometry control facilities. Further the IC generates the drive waveforms for DC coupled vertical boosters

to the TDA9302H.

Horizontal Oscillator

The oscillator is of the relaxation type and requires a capacitor of 1nF C446 at pin29. The maximum oscillator

frequency is determined by a resistor R403 4.7K form pin28 to ground.

PLL 1 Phase Detector

The phase detector is a standard one using switched current sources. It compares the middle of H-sync. with a

fixed point on the oscillator saw-tooth voltage. The PLL loop filter C401,R401,C402 is connected to Pin26.

PLL2 Phase Detector

This phase detector is similar to the PLL1 detector and compares the line flyback pulse at pin 1 with the

oscillator saw-tooth voltage. The PLL2 detector thus compensates for the delay in the external H-deflection

circuit by adjusting the phase of the HDRV output pulses. The phase between H-flyback and H-sync can be

controlled at pin30.

X-ray Protection

The X-ray protection input pin25 provides a voltage detector with a precise threshold. If the voltage exceeds this

threshold for a certain time, an internal latch switches the whole IC into protection mode. In this mode several

pins are forced into defined states:

Pin7 (BDRV) is floating

Pin6 (HDRV) is floating

Pin12, 13 ( VOUT 1, 2) are floating

Vertical Oscillator

The vertical free –running frequency is determined by the resistor R608 at pin23, with capacitor C604 at pin24.

Usually the free-running frequency should be lower than the minimum trigger frequency.