Checking Saw Filter - LG C3100 Service Manual

4.2.5 Checking SAW Filter

FL401 FL402
Figure 4-7.
Check RF Level of
Saw Filter Input
For GSM : FL401.1
Check RF Level of
Saw Filter Input
For GSM : FL401.3
For DCS : FL402.3
For the test,
RX Stand alone Mode is needed.
Refer to chapter 11
C422
No
FL401.1 : ~ -61dBm
Check the parts are well
Yes
Soldered
For GSM : C422
FL401.3: ~ -64dBm
No
FL402.3: ~ -64dBm
Check the parts are
well Soldered.
For GSM : L402,C420
Yes
For DCS : L403, C425
Saw Filter is OK.
See next Page to check
Rx IQ Signal.
- 41 -
2 3
G1 O1
1
IN
FL401
EFCH942MTCA7 G2 O2
27p
5 4
2 3
1 G1 O1
IN
FL402
EFCH1842TCA7 G2 O2
5 4
Changing
C422 for GSM
Soldering is
OK?
No
Changing
L402, C420 for GSM
L403, C425 for DCS
4. TROUBLE SHOOTING
C420
1p
L402
27nH
C423
1p
C425
1p
L403
7.5nH
C428
1p
Changing FL401
Yes
for GSM, FL402
for DCS