3
、
The time clock circuit is composed by 27MHz, 24.576MHz crystal oscillator and
their multiple frequency circuits. The time clock ACLK of WM8739 can be produced by
24.576MHz crystal oscillator’s half frequency. 27MHz crystal oscillator can provide
ES6128 and time clock of ES7010. The following is part circuit figure of it:
Figure
6
、
Time clock circuit
From the above figure, you will see that the time clock circuit is mainly composed
by 27MHz, 24.576MHz crystal oscillator, so the stability of crystal oscillator count for
much the reliability of system. In the case of no picture after power on, you should
check 27MHz, 24.576MHz crystal oscillator besides IC reset signal. Check the output
frequency of crystal frequency after passing the IC and check the frequency that
reached to all composite chips.
4
、
I2C signal circuit controlled memory 24C01, X1226, video decoding composite
SAA7114, TUNER in the whole system. I2C signal check 24C01, SAA7114, TUNER
and initialize all these chips in the process of unit power on. 2C signal controlled the
signal of 24C01, SAA7114, X1226, TUNER after unit worked. Following figure 7 is
about the signal connecting process.
Figure 7
、
I2C signal connecting
(5) 16M FLASH software controls circuit, the circuit is mainly composed by FLASH and
its software. The 16M FLASH controls the work of unit and the software controlling
of system. 16M FLASH AM29LV1600B can be re-writable by disc.
Ⅳ
Mainboard troubleshooting check flow
Mainboard troubleshooting should be in the case of all groups of output voltage of
