LG KG110 Service Manual page 34

Check ANT SW
R427
Vmod_en
Operating Mode
TX GSM 850/900
TX DCS/PCS
RX1
RX2
RX3
RX4
Sleep Mode
Check R418,R427
Check whether Ant SW
Set as RX mode
? Refer to Table 4-2
Check RX level of
R441 (for GSM850)
R444 (for EGSM)
R445 (for DCS)
R446 (for PCS)
R418
Vtx
Figure 4-6
Vmod_en
H
H
H
H
H
H
L
Figure 4-6
Vmod_en = H?
Vtx = L?
YES
~ -62dBm?
YES
See next page to check
SAW filter
33
4. TROUBLE SHOOTING
C441 C444
RX4 RX3
Control Voltage
Vtx Vbs1
H L
H H
L L
L L
L H
L H
L L
NO
Change the board
NO
C445 C446
RX2 RX1
Vbs2
L
L
L
H
L
H
L
Change U401