LG H990ds - LTE Tx Signal Path (Bands B1-B39)

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reserved. Only training and service purposes
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3. TROUBLE SHOOTING
Image
Checking Tx signal path(LTE B1/B2/B3/B4/B5/B8/B12/B17/B20/B26/B28/B34/B39 Tx)
Check TP1/TP3
+VPA0 OK?
START
The Problem may be
other part and
Check QFE2101 Logic part
NO
The Problem may be
other part and
Check QFE2101 Logic part
Check TP2
3.2V≤TP2≤4.2V?
Check TP4~13
If LTE of All band
Over 22dBm?
NO
Check next step
Check component
above RF signal path
and FEMid Block
YES
YES
Replace U1301
NO
Check
Transceiver
physical damage
or soldering
condition
OK
NOT GOOD
Replace U1400
YES
NO
YES
Check TP4~13
If LTE of All band
Over 10dBm?
TP1(+VPA0)
TP2(+VPWR_BOOST_BYPASS_RF)
U1601
3.5.3 LTE PART – B1/B2/B3/B4/B5/B8/B12/B17/B20/B26/B28/B39 Tx
TP5(B2 Tx)
TP7(B5/26 Tx)
U1301
(MMPA)
TP13(B39 Tx)
TP6(B3/4 Tx)
TP11(B28A Tx)
TP4(B1 Tx)
BOTTOM
TP10(B20 Tx)
TP8(B8 Tx)
TP9(B12/17 Tx)
TP12(B28B Tx)
TP3(+VPA0)
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