LG KP270 Service Manual page 109

4. TROUBLE SHOOTING
4.17.4 Checking GSM Tx part
Setup Test Equipment
Cell Power = -60dBm
Tx Power Level set
(EGSM=5,DCS=0,PCS=0)
Is the level
of TP4~6 same to Table.1?
YES
Check TP2,TP3
TP2(EGSM 900) 33dBm over?
TP3(DCS, PCS) 30dBm over?
YES
Check TP1
EGSM 900 31dBm
DCS1800 29 dBm
PCS1900 29 dBm
YES
GSM Tx Path is OK
TP2 TP2
TP3 TP3
TP2 TP2
TP5 TP5
LGE Internal Use Only
NO
Over?
TP4: check U103
TP5: check U103
TP6: check VBAT line
Remove U503 and
Check the power of
pin1,pin7 (on board)
The power of pin1,pin7
is 0~3dBm?
YES
Replace
U503
TP1 TP1
TP4 TP4
Copyright © 2008 LG Electronics. Inc. All right reserved.
- 110 -
NO
Check U504
or
Replace U504
Only for training and service purposes