LG U990 Service Manual page 102

4.5.2 Checking UMTS PAM Control Block
• PAM control signal
1. PWR_DET : UMTS Tx Power Detected value (Check R123)
2. TX_AGC_ADJ : UMTS RTR6275 Tx Amp Gain Control
3. VREG_TCXO_2.85V : UMTS PAM enable (about 2.85V)
4. +VPWR : UMTS PAM Main Voltage ( 3V < +VPWR < 4.2V)
5. PA_ON : Turns the PA on and off
6. PA_R1 : Control signals that step the active PA mode and bias
VREG_TCXO_2.85V
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4. TROUBLE SHOOTING
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+VPWR
R123
UMTS2100
Coupler
LGE Internal Use Only