Bluetooth Trouble - LG U990 Service Manual

4.15 Bluetooth trouble

Bluetooth supplied voltages are generated by the PM6650.
Those signal's path are : PM6650 → VREG_MSMP_2.7V and VREG_BT_2.85V is asserted →
TCXO_BT 19.2MHz is asserted → Bluetooth ON → BT_TX_RX_N is High → BT serial interface
control is operated (SBST / SBCK / SBDT)
BT_CLK
C803
1u
VREG_MSMP_2.7V
C811
100p
VREG_TCXO_2.85V
TCXO_PM
RTR6275_TCXO
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Only for training and service purposes
C800
L800
LBRQ-2B43A
C801 1000p 9
CLK_REF
3
VCC_OUT
2
VDD_INT
10
VDD_MSM
C804
14
1u VDD_BAT
VREG_BT_2.85V
C812 C813 C814
0.1u 100p
2.2u
3
4
C139 C140
0.1u 1000p
C144 1000p
C147 1000p C148
Figure. Schematic of Bluetooth Interface
4. TROUBLE SHOOTING
NA
BT_ANT BT_GND
NA
BLUETOOTH
LG INNOTEK
M800
4 TP800
SBST
11 TP801
SBCK
12 TP802
SBDT
5
SYNC_DET_TX_EN
13
RX_BB_TX_BB
7
XTAL_IN
TCXO
X100
OUT GND
2
R115 100ohm
VCC VCONT
1
19.2MHz
C141
0.01u
C145
R120 100K
1000p
8200p
U102
TC7SH04FS
- 145 -
BT_SBST
BT_SBCK
BT_SBDT
BT_TX_RX_N
R807
0
BT_DATA
C802 1000p
TCXO_BT
TRK_LO_ADJ
VREG_BT_2.85V
TCXO_BT
LGE Internal Use Only