Samsung SGH-P400 Service Manual page 24

7. EGSM Reciever
CONTINUOUS RX ON
RF INPUT : 62CH
AMP : -50dBm
NORMAL CONDITION
catch the channel?
U1005 CHECK
pin15 ≥ -65dBm ?
U1005 CHECK
pin1, 2 ≥ -65dBm ?
U901 CHECK
pin21,22 ≥ -65dBm ?
U901
pin 12,13≥
-20dBm ?
YES
U901 CHECK
pin
14,23,26,32:
clean 2.8V?
YES
U901 pin3,4
Vp-p :
240mV?
YES
U901 pin1, 2
Vp-p : 250mV
?
YES
U900 pin
2,3,4,5 Vp-p
: 100mV ?
YES
YES
YES
YES
YES
NO
U902 CHECK
pin5,25,28 :
3V ?
YES
U902 CHECK
pin 7 : 13MHz ?
Vp-p : 860mV?
YES
U902 change or
resolder
NO
U100pin39, C111
check or resolder
NO
NO
resolder or change
CHECK
U700
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SGH-P400 Flow Chart of Troubleshooting
NO
Check soldered status of
L1000, L1003
CN1001
NO
resolder or change
NO U1005
resolder or change
NO
C1003,C1004,L1001
resolder or change
NO
U100pin33 , C110
check or resolder
NO
OSC801 CHECK
pin 3 : 13MHz ?
Vp-p : 950mV?
C804,R803
resolder
U900 CHECK
pin6, 20 : 2.8V ?
YES
U900
resolder or change
U901
NO
3-13
OSC801
NO
CHECK
pin 4 : clean
YES
OSC801 change or
resolder
NO
U100pin33, C110
check or resolder
NO
3V ?
YES