Only For Training And Service Purposes - LG TU550 Service Manual

4. TROUBLE SHOOTING
GSM900/GSM850 TX
DCS/PCS TX
GSM 850 RX
UMTS 850
DCS RX
PCS RX
UMTS 1900
GSM900 RX
Checking Switch Block power source
Check Soldering of
ANT_SEL0, 1, 2 High Level
2.5V < Voltgae < 3.0V
LGE Internal Use Only
ANTENNA SWITCH MODULE LOGIC
IN_A
HIGH
HIGH
LOW
HIGH
LOW
LOW
HIGH
LOW
Logic Table of the Antenna Switch
YES
Check the Logic
in each mode
IN_B
HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
LOW
Check VCC
NO
TP1 VREG_RFRX_0_2.85V
Copyright © 2007 LG Electronics. Inc. All right reserved.
- 76 -
IN_C
LOW
LOW
LOW
HIGH
HIGH
HIGH
HIGH
LOW

Only for training and service purposes