LG H990ds - LTE Tx Signal Path (Bands B7, B38, B40, B41)

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3. TROUBLE SHOOTING
Checking Flow Image
Checking Tx signal path(LTE B7/B38/40/41)
TOP
START
NO
The Problem may be
other part and
Check QFE2101 Logic part
Check TP2
3.2V≤TP2≤4.2V?
Check TP3
If LTE B7/B38 Tx Power
Over 22dBm?
NO
Check next step
Check component
above RF signal path
YES
YES
Replace U1300
NO
Check Transceiver
physical damage or
soldering condition
OK
NOT GOOD
Replace U1400
YES
NO
YES
Check TP4/TP5
If LTE B7/B38 Tx Power
Over -5dBm?
Check TP1
+VPA0 OK?
The Problem may be
other part and
Check QFE2101 Logic part
3.5.4 LTE PART – B7/B38/B40/41 Tx
TP1(+VPA0)
U1300
(HB PAM)
TP2(+VPWR_BOOST_BYPASS_RF)
TP3(B7/B38 TX)
TP4(B38 TX)
TP5(B7 TX)
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