Acer AL1702 AL1702 Service Guide - Page 9

AL1702 3.6 Audio (Circuit diagrams MAIN PWB 8 of 8) [OPTION] 3.6.1 P309 connector The audio signal input received from the audio input terminal P309 from the jack input of the jack board, P309 is applied to amplifier I311 of pin4 (L-CH) and pin9 (R-CH) through the low-pass filter consisting of R417, R418, C419 and C420. 3.6.2 P310 connector The audio signal is output to the audio output terminal P310, and to the internal speaker system. 3.6.3 I310MOSFET I310 MOSFET (CEM9435A) is cut audio power (12V) for the power save sequence. The signal (AUDIO_EN) is ON/OFF I310 MOSFET through the Q311 control. 3.6.4 I311amplifier The I311 TDA7496L is audio amplifier, I311 operated power voltage is 12V. I311 pin4 and pin9 is audio input port. I311 pin14 and pin17 is audio output port. I311 pin 12 is mute input from I307 MCU. The pin 6 is audio volume from the I305 MST8111B. 4 Others 4.1 Detection of POWER switch status The MCU identifies the ON status of the two power supplies. The identification is made when the power supply is turn off. For example, if the power supply is turn off with the POWER switch, the POWER switch must be turn on when active the power supply again. If the power supply is turned off by pulling out the power cord, then this power supply can be turned on by connecting the power cord, without pressing the POWER switch. 4.2 Display mode identification 4.2.1 Display mode identification The display mode of input signal is identified based on Table 2. When the mode has been identified through the measurement of horizontal and vertical frequencies, the total number of lines is determined with a formula of "Horizontal frequency / Vertical frequency = Total number of number of lines". Final identification can be made by examining the coincidence of the obtained figure with the number of lines for the mode identified from the frequency. The Distinction Hsync and Vsync of each mode is shown in Table 3. When the detected frequency if the sync signal has changed, the total number of lines should be counted even through it is range identified frequency in the same mode. 4.2.2 Out of range This out of range mode is assumed when the frequency out of the horizontal / vertical signal is as specified below. Vertical frequency : 56 ~ 76 Hz. Horizontal frequency : 30 ~ 81.1KHz. 4.2.3 Power save mode The power save mode is assumed when the horizontal / vertical signals are as specified below. If there is no horizontal sync signal input. If there is no vertical sync signal input. If the horizontal sync signal is outside the measuring range of MST8111B. If the vertical sync signal is outside the measuring range of MST8111B. Page 7