Samsung SGH-A400 Service Manual
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SAMSUNG Proprietary-Contents may change without notice
5-11
SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram
5-11 SGH-A400 GSM Receiver
RX On
RF input : 62 CH
Amp. : -50 dBm
Y
N
N
Y
U505
Pin 9
≥ -65 dBm
Resolder or Change CN500
Y
F501
pin 5
≥ -73 dBm
Resolder
F501
N
Y
F300
pin 4
≥-30 dBm
Change
F300
N
Y
Check the
signal at U300
pin 26, 27
Change
U300
N
Y
U505
Pin 5
≥ -65 dBm
N
Y
Resolder& U505
Pin 5 ≥ -65 dBm
Check voltage
U505 pins
Pin 2 : L
Pin 4 : H
Pin 8 : H
Pin 10 : L
N
Y
U507
pin 16, 17
≥ -40 dBm
Y
Check OSC300
pin 1 ≥ -10 dBm
Change OSC300
Change U507
Y
Change U300
END
N
N
Y
F301
pin 1, 2, 5, 6
≥ -47 dBm
Change F301
N
Y
F300
pin 1
≥ -25 dBm
Check D300
pin 1 ≥ 1V~2.3V
Resolder or change
D300
N
1
2
3
4
5
6
7
8