Gsm Receiver - Samsung SGH-X490 Service Manual

Flow Chart of Troubleshooting

7-11. GSM Receiver

RX ON
RF input : CH center freq
Amp : -50dBm
Y e s
U100 Pin7
> = -65dBm
Y e s
U100 pin5
> = -65dBm
Y e s
F101 pin1
> = -70dBm
Y e s
U101
pin32 > = -70dBm
pin33 > = -70dBm
Y e s
U101 pin6 , 7 , 8 , 9
> = 1V
Y e s
R130 , R 131 , R 132
, R 133 > = 1V
Y e s
Check U202
END
No
Resolder CN101, C102
No
No
Resolder F101, C107, L115
No
Resolder L112, L113, L114
No
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Check U100
pin2= L , p in4= L , p in8= L
Y e s
Check U101
pin10 , 2 2 , 2 8 > = 2 .7V
pin20 > = 4 .0V
Y e s
7- 22
No
Check ANT Switch
control circuit
Resolder U100
No
Check & Resolder
RF PSU Part
Check & R esolder
U101, RF26MHz part,
R104 , R105