Trouble Shooting Chart
No supply at power on
YES
YES
YES
YES
NO
NO
NO
Check point: PCON
Observe: Use an oscilloscope to
measure the PCON voltage output
jumps from0.7V to 0V.
Check point: L305
Observe: The waveform at Gate terminal is normal.
The pin4 of Cn303 is 5V.
Check if VA+ VA- +2.5V are Ok
Solution: Replace Q302 Q303 U304 if damaged
Solution:
Short PCON to GND and voltage
output restored Replace the CPU IC
on front panel
Observe: Check D311
Solution: Replace if damaged
Replace Q306
GO
Stand LED Light up
Not supply voltage output
when press power key
Check point: Measure Q306
Observe:
?
BASE terminal Q306 is 0V
?
Collection terminal of Q306 is 5V
Check point: Pin4 of Cn303
Observe: the voltage should be +5V
4-2