LG GS290 Service Manual page 49

4. TROUBLE SHOOTING
Checking Flow
Check Control Signals
(TP1 TP2 TP3)
Signals are
Normal ?
Yes
PAM Control Signal is OK.
See next page to check
FEM & Mobile SW Circuit.
Figure 26. GSMK Control Signal
TP1(PA LEVEL)
TP2(TXON PA)
TP3(PA MODE)
TP1(PA LEVEL)
TP2(TXON PA)
TP3(PA MODE)
LGE Internal Use Only - 98 -
Check
No
PMB8877(U100)
Figure 27. 8PSK Control Signal
TP2(TXON PA)
TP1(PA LEVEL)
TP3(PA MODE)
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4.13.6 Checking Mobile SW & FEM
Mobile SW & FEM Circuit Diagram
TP1
SW500
TP2
KMS-518_P TP1 TP2
G1
C524
A
C ANT
17
22p
G2
L501
C539
100n
DNI
Figure 8. Mobile SW & FEM Circuit
Checking Points
FL50
TP2
SW500
TP1
Figure 9. Mobile SW & FEM
Table 2. FEM TX Control Logic
EGSM/GSM850 DCS/PCS
VC1 ON OFF
VC2 OFF ON
Copyright © 2010 LG Electronics. Inc. All right reserved. - 99 -
Only for training and service purposes
4. TROUBLE SHOOTING
R502 100
VC1
R504 100
VC2
TP3
C503 C508
47p 47p
TP3
FL500
LMSP43NA-782
TP3_C508
TP5 ~ 8
TP4_C503
LGE Internal Use Only