Check Saw Filter - LG KG110 Service Manual

4. TROUBLE SHOOTING

4.2.4 Check SAW filter

FL401
FL403
FL402
C441
C444
C445
C446
Check RF level of
SAW filter input
For GSM850 FL403.2
For EGSM FL401.9
For DCS FL401.6
For PCS FL402.2
Check RF level of
SAW filter output
For GSM850 FL403.4 & F403.6
For EGSM FL401.1 & FL401.2
For DCS FL401.3 & FL401.4
For PCS FL402.4 & FL402.6
F L403
856441
100P
Q1
2
I N
Q2
G1 G2 G3
100P
9
100P
6
100P
2
Input = -61dBm ?
Output = -64dBm?
See next page to check
I/Q signal
Figure 4-7
4
6
FL401
856520
1
G_01
2
G_I N G_02
3
D _01
4
D _I N D _02
FL401
856417
4
Q1
I N
6
Q2
G1 G2 G3
NO
YES
NO
YES
34
C441
~C446
C 442 56P
L408
33nH
C 443 56P
C 415 68P
L401
18nH
C 416 68P
C 417 39P
L402
7. 5nH
C 418 39P
C 419 47P
L403
6. 8nH
C 420 47P
Change the capacitor
C441 for GSM850
C444 for EGSM
C445 for DCS
C446 for PCS
Change the SAW filter
FL403 for GSM850
FL401 for GSM & DCS
FL402 for PCS