LG F1200 Service Manual page 81

4. TROUBLE SHOOTING
Checking Flow
Check Control Signals
of U102 Refer to Waveform
Check if there is any
Major Difference
Tx PAM Circuit Diagram
PA_BAND
PA_ON
APC
Waveform
Similar ?
Tx IQ signals are OK.
Go to the next stage
R106
R105 100
100
C114
1000p
R104
10K
C562
27p
R559
PDNB
390
RF_EN
R555
26MHz
0
PA_BAND
APC
PA_ON
Redownload
No
Yes
BS
4
PAC_ENABLE
2
GSM_IN
6
C116
1000p DCS_PCS_IN
5
VBAT
C102
1000p
C103 C117
33u
22p
- 80 -
phone S/W
C108
RSVD
15
NA
C109
100p
L100
NA
SKY77325
U100 GSM_OUT
12
DCS_PCS_OUT
17
C106
C105 C107
12p
NA NA
C104 C115
0.01u 0.01u