Service manual

Page 6
AL1702
3.5.3X302 crystal
The X302 crystal is 11.0592MHz, support the operated clock to the MCU.
3.5.4Reset circuit
The C396, R379, D316 is support reset signal to the MCU, then MCU have output hardware reset signal
(HWRESET) to the scaler.
3.5.5I308 EEPROM
The I308 is 24LC16 EEPROM, the data transfer between I308 and MCU is effected through the IIC bus
SCL (pin14) and SDA (pin13) of MCU. The OSD related setting data, I305 control data and other service
data, to be stored in I308.
3.5.6P308 connector
The P308 has support keypad function. Control is give effect to for the push switch to be used when
the user changes the parameters, in order to modify the respective setting values. Whether the switch
has been pressed is identified with the switch input level that is turned “L”.
Each switch input port is pulled up at outside of MCU. Related ports of I307 based on Table 1.
Each parameter is stored in the I308 EEPROM, the contents of which are updated as required.
The P308 have LED Green and Amber light, the LED Green signal pin 36 from I307 MCU, and the LED
Amber signal pin 37 from I307 MCU.
Table 1 Related ports of I307
Pin No. I/O Signal name Function Remarks
Pin 3 I KEY_POWER Soft power switch input Power key
Pin 2 I KEY_MENU Exit/Enter switch input Enter / withdraw from
OSD
Pin 41 I KEY_DOWN
↓ switch input
Down key
Pin 42 I KEY_MINUS
← switch input
- / Mute key
Pin 1 I KEY_PLUS
→ switch input
+ / Auto key
3.5.7Audio control function
The I307 MCU output signal control audio mute and power, the pin33 is mute signal, the pin32 is
controlled audio power signal.
3.5.8Scaler programmed function
The I307 MCU is used DDR direct bus, between I305 MST8111B and MCU I307.
3.5.9ISP and DDC2Bi function
The DDC2Bi is VESA standard for the host PC system, it can through DDC2Bi bus control LCD monitor.
The I309 will off DDC_CLK and DDC_DAT signal, when LCD monitor is no power.
Can use ISP function for firmware modification.
The pin29 is bus clock (DDC_CLK), the pin28 is bus data (DDC_DAT). It is same of the IIC data bus.
3.5.10The power save sequence function
First disable I307 pin31 (BKLT_EN) from H to L of LCD module back light power, delay some time, then
disable I307 pin9 (PANELVCC_EN) from H to L of LCD module power, and disable I307 pin32
(AUDIO_EN) from H to L of audio power, and through 3-wire bus programmed I305 MST8111B to
power down mode.