Gsm Transmit - Samsung SGH-A200 Service Manual

5-12 GSM Transmit

Flow chart of Troubleshooting and Circuit Diagram
Tx On (level : 5)
U304
Yes
Pin 2
≥ 30 dBm
No
U304
Yes
Pin 7
≥ 30 dBm
No
Yes
U312
Pin 4
≥ 30 dBm
No
U312
Yes
Pin 1
≥ 0 dBm
No
U200
Yes
Pin 6
≥ 7 dBm
No
U200
No
Pin 7 ≤ 0.5 V
Pin 5 ≥ 2.8 V
Pin 3 = 0.5~2.5 V
Yes
U305
No
pin 30, 47
≥ -10 dBm
Yes
U305
No
Pin 17, 18, 19, 20
≥ 40 mV
Yes
Check U305
No
Pin 38 ≥ 2.5 V
Pin 35 ≤ 0.5 V
Yes
Resolder
U108
Resolder
J301
Check
VC1 : H
VC2 : L
VC3 : L
No
Resolder
U318, C353
Check
U312 : +VBATT
Pin 2 (APC)
OK?
No
Resolder or Change
C698, R335, R364, R366
Resolder
U108, U457, U200
Resolder
U302
Resolder
OneC(U108)
Resolder
U305 (Pin35, Pin38)
Yes
Change or Resolder
U304
Check
Ant. S/W, Control Circuit
Yes
Resolder or
Change U312
Check +VBATT
or APC Control
5-19