LG KM380t Service Manual page 90

6.14.1 Transmitter Circuit
Transmitter Circuit
Does Power
(C543 & C548)
seem like
about 2dBm?
YES
Check the next part
GND25
27
GND24
28
GND23
29
GND22
30
GND21
31
GND20
32
GND19
33
GND18
34
GND17
U501
35
GND16
SKY77340
36
GSM_OUT
9
GND5
10
GND4
11
RSVD2
12
GND3
13
GND2
14
GND1 DCS_PCS_IN
15
DCS_PCS_OUT
16
√ Check point of PAM
- Transmitter output power (=C548, C543) is approximately 2dBm.
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
NO
Check
U102
Fig 13 Transmitter circuit (U102)
GND15
26
GND14
25
GND13
24
GND12
23
GND11
22
GND10
VSUPPLY
21
GND9
20
GND8
19
GND7
18
GND6
17
EN
8
GSM_IN
7
VRAMP
6
VBATT
5
RSVD1
4
BS
3
2
MODE
1
C561 C562 C563
C560
0.1u 1u 33 uF 39p
- 91 -
C543
C539 C540
DNI DNI
R591 47
C543 100p
R520
C548
C564 C565 C566 C572 C567
39p 39p 39p 39p DNI
6. Trouble shooting
C548
PA_EN
TXLB
47
TX_RAMP
R522 47
PA_BAND
TXHB
100p
R523 47
PA_MODE_2
C568
DNI
LGE Internal Use Only