LG PX8700 Service Manual page 69

PX8700
4.2.1.6. Check DCN PAM Circuit
Test Point
PIN11 RF OUT PIN11 RF OUT
PIN3 PA_R1 PIN3 PA_R1
U108 U108
PIN2 RF IN PIN2 RF IN
PIN1 VREF CELL PIN1 VREF CELL
LG Electronics Inc.
Check U108 Pin 2,11 Check U108 Pin 2,11
Refer to Graph 4.2.12 Refer to Graph 4.2.12
Check U108 Pin4 Check U108 Pin4
Check U108 Pin2 Check U108 Pin2
PIN4 VCC PIN4 VCC
Check U108 Pin3 Check U108 Pin3
Checking Flow
START START
RF IN/RF OUT RF IN/RF OUT
YES YES
Similar ? Similar ?
NO NO
NO NO
≥ 3.8V ? ≥ 3.8V ?
YES YES
YES YES
≥ 2.7V ? ≥ 2.7V ?
NO NO
NO NO
≤ 1.8V ? ≤ 1.8V ?
YES YES
Replace U108 Replace U108
PAM Circuit OK. PAM Circuit OK.
See next page. See next page.
Check VCC Line Check VCC Line
Check +2.9V_TX Line. Check +2.9V_TX Line.
And PA_ON. And PA_ON.
Check PA_R1 Signal line Check PA_R1 Signal line
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