SGH-N500 Flow Chart of Troubleshooting and Circuit Diagrams
5-2
1
5-12 GSM Transmitter
Tx On (level : 5)
U203
Pin 8
≥
30 dBm
U203
Pin 5
≥
30 dBm
U625
Pin 3
≥
30 dBm
U476
Pin
1
≥
-
1
0 dBm
U200
Pin 6
≥
-
1
0 dBm
U200
Pin 7 0.5 V
Pin 5
≥
2.8 V
Pin 3 = 0.5~2.5 V
Resolder
CN
1
Check
VC
1
: L
VC2 : H
Change or Resolder
U203
Resolder
U625, C264
Resolder
C204, R2
1
4, R2
1
7, R753, R203
Resolder
U478
U454
pin 30, 47
≥
-
1
0 dBm
Check U454
Pin 38
≥
2.5 V
Pin 35 0.5 V
Resolder
U454 (Pin35, Pin38)
Check U6
1
8
Resolder
U6
1
8
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Check
Ant. S/W Control Circuit
Check
U476 : +VBATT,
Pin 2 (APC)
OK?
Resolder or
Change U476
Yes
Check +VBATT
or APC Control
No
U454
Pin
1
7,
1
8,
1
9, 20
≥
40 mV
Resolder
OneC(U6
1
8)
Check
U200 Pin 3.
OK?
No
Yes
Yes
Resolder
U454, U200
Resolder U200 &
Check Pin 7, 5 path
No