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3.3.2 Troubleshooting flow chart
[ Flow chart 1 ] Trouble symptom: standby light is not on
Trouble description: connect with power, standby indicator light is not on, machine has no response
and buttons have no function.
Check flat cable from power
board to video main board
N
Y
Y
Machine not power on
Check
whether Cn6 pin 2
12Vvoltage is
normal
Whether
12V voltage
outputted by power
board is
normal
Check
the power supply
loop from +5VEXT power
toMST718 is
normal
Y
N
Change U503
Check
whether U503 pin 2
5V voltage is
normal
Check power board
N
Check power supply loop
Y
N
Check
whether standby
control signal outputted
by MST718_57 is
normal
Y
N
Check
whether reset
signal of MST718
is normal
N
Check reset system circuit
Y
Check
whether X101 clock
signal is
normal
N
Check clock system circuit
Y
Change MST718
Check
whether Q117 is
normal
(Remark: Q117_C is low
level in standby and high
level when working normally)
Y
Check the standby indication
circuit on subsidiary board
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