LG GB210 - Page 46

- 47 -
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Only for training and service purposes
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4. TROUBLE SHOOTING
(1) Checking Crystal Circuit
Graph 4.2.1(a)
WAVEFORM
Graph 4.2.1(b)
26 MHz O.K?
No
Crystal Circuit is OK
See next Page to check
Mobile SW
See next Page to check
Mobile SW
Yes
Change X500
TEST POINT
CIRCUIT
CHECKING FLOW
TP1
X401
TP2
TP1
TP2
12
13
VDD
15
VLDO1
VLDO2
16
RX1900B
RX900
RX900B
18
VAFC_NC
VBAT
14
24
VCC_BBQ
VCC_REF
17
VCC_TXVCO
AD6548
U501
Q
23 22
QB
20
REFIN
REFINB
19
REF_OP
21
RX1800
RX1800B
RX1900
0.1u
C509
2V75_VVCXO
TP1
0R507
26MHz_BT
26M_DBB
TP2