LG MG210 Service Manual page 82

Checking Regulator Circuit (Tx pass continued)
Checking Points
U403
PIN6
PIN1 PIN3 (RF_EN)
(VBAT) (RF2,85V)
LDO Circuit Diagram
RF2.85V
R1114D281D-TR-F U403
3 1
VOUT VDD
2 4
GND1 NC
5 6
GND2 CE
C440
1u
Checking Flow
Pin 3
Regulator Circuit is OK.
See next page to check
VCTCXO Circuit.
VBAT
RF_EN
C441
C442 1u
1u
- 81 -
4. TROUBLE SHOOTING
Check Pin 1
No
3.4 ~ 4.2 V ? Check Battery
Yes
No
Pin 6 High ? Check DBB[U101]
Yes
No
Replace Regulator
≡
2.85V ?
[U403]
Yes
Waveform
Paging Period 5