Videocon Mstar MST719, Mstar MST719DU, Руководство по обслуживанию

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MST719 Service Manual
30
6. Usual fault
1) , Can’t work(fault description: LED is off or red LED is always on )
Firstly confirm if the AC power supply
mains Switch is ok, and then Check if the
red LED is on
1. Check the 5V_STB have +5V or not. If OK
please check main chassis.
2.
If 5V_STB abnormity, pull out the power
supply connector, Then retest the 5V_STB, if
become OK main chassis problem, if still
abnormity the power supply board problem.
N
Y
Check if the I2C of U18 pin61,pin62 and the
U21 I2C pin software data is ok. Check U20
flash IC is work and the software data
normal operation.
Check if the crystal is work, it frequency is
+12M, check the Q28 reset circuit normal
working.
N
N
Y
Y
N
LED Not on
can’t power on
If all the work condition are ready but still
can’t power on ,Please try to change
MST719 main IC.
Y
N
Check if the voltage of the U2 output is
3.3V, the U1 output is 1.2V and check the
relevant voltage get to the MST719 IC pins.