Samsung SGH-X481 User manual

GSM TELEPHONE
SGH-X481
GSM TELEPHONE CONTENTS
1. Specification
2. Flow Chart of Troubleshooting
3. Exploded View and Parts List
4. Electrical Parts List
5. PCB Diagrams
6. Block Diagrams
7. Disassembly and
Assembly instructions

1. SGH-X481 Specification
1-1
1-1. GSM General Specification
GSM900
Phase 1
EGSM 900
Phase 2
DCS1800
Phase 1 PCS1900
Freq. Band[MHz]
Uplink/Downlink
890~915
935~960
880~915
925~960
1710~1785
1805~1880
1850~1910
1930~1990
ARFCN range 1~124 0~124 &
975~1023 512~885 512~810
Tx/Rx spacing 45MHz 45MHz 95MHz 80MHz
Mod. Bit rate/
Bit Period
270.833kbps
3.692us
270.833kbps
3.692us
270.833kbps
3.692us
270.833kbps
3.692us
Time Slot
Period/Frame
Period
576.9us
4.615ms
576.9us
4.615ms
576.9us
4.615ms
576.9us
4.615ms
Modulation 0.3GMSK 0.3GMSK 0.3GMSK 0.3GMSK
MS Power 33dBm~13dBm 33dBm~5dBm 30dBm~0dBm 30dBm~0dBm
Power Class 5pcl ~ 15pcl 5pcl ~ 19pcl 0pcl ~ 15pcl 0pcl ~ 15pcl
Sensitivity -102dBm -102dBm -100dBm -100dBm
TDMA Mux 8 8 8 8
Cell Radius 35Km 35Km 2Km -

SGH-X481 Speclflcation
1-2
1-2. GSM Tx Power Class
TX Power
control level GSM900
5 33±2 dBm
6 31±2 dBm
7 29±2 dBm
8 27±2 dBm
9 25±2 dBm
10 23±2 dBm
11 21±2 dBm
12 19±2 dBm
13 17±2 dBm
14 15±2 dBm
15 13±2 dBm
16 11±3 dBm
17 9±3dBm
18 7±3 dBm
19 5±3 dBm
TX Power
control level DCS1800
0 30±3 dBm
1 28±3 dBm
2 26±3 dBm
3 24±3 dBm
4 22±3 dBm
5 20±3 dBm
6 18±3 dBm
7 16±3 dBm
8 14±3 dBm
9 12±4 dBm
10 10±4 dBm
11 8±4dBm
12 6±4 dBm
13 4±4 dBm
14 2±5 dBm
15 0±5 dBm
TX Power
control level PCS1900
0 30±3 dBm
1 28±3 dBm
2 26±3 dBm
3 24±3 dBm
4 22±3 dBm
5 20±3 dBm
6 18±3 dBm
7 16±3 dBm
8 14±3 dBm
9 12±4 dBm
10 10±4 dBm
11 8±4dBm
12 6±4 dBm
13 4±4 dBm
14 2±5 dBm
15 0±5 dBm

2. SGH-X481 Flow Chart of Troubleshooting
2-1
2-1. Baseband
2-1-1. Power ON
check the current
consumption
>= 100mA Download again
'Power ON' does not work
No
Yes
Yes
END
Yes
Check the Initial Operation
Yes
Charge the battery
No
Check the Voltage
of the Battery
>= 3.3V
check keypad
No
Check the pin C101,
C102,C103 of U100
is
>=2.8V
Check
"Power On"
key?
No
check U100 and C101
Yes 1
Check the clock
signal at pin #4 of
OSC600
No Check the clock generation
circuit OSC600
Yes
2

SGH-X481 Flow Chart of Troubleshooting
2-2

SGH-X481 Flow Chart of Troubleshooting
2-3
2-1-2. Initial
Initial Failure
check the pin
RSTB of U600 is
LOW?
Check U600
No
Yes
Yes
END
Yes
Check the Initial Operation
Yes
Check
R800,R801,C811,R803
No
check the pin CKI
of U600 is 13Mhz?
Check the clock
signal at pin #3 of
OSC600
No check OSC600
1
Check the pin #9 of
U600 is HIGH and pin
#11, #13 is 2.9V?
No Check U100
Yes
2
3
4

SGH-X481 Flow Chart of Troubleshooting
2-4

SGH-X481 Flow Chart of Troubleshooting
2-5
END
No
Yes
2
Check the SIM Card
"Insert SIM" is displayed on the LCD
Is there any signal
pin #2,3,4 of CN100?
Check the U100
Check the U100 & U600
No
Yes
1
The voltage is 2.8V
at the pin#1 of CN100
2-1-3. Sim Part

SGH-X481 Flow Chart of Troubleshooting
2-6

SGH-X481 Flow Chart of Troubleshooting
2-7
2-1-4.Microphone Part
* Call with Sim before testing.
Check the soldered
status of microphone
MicroPhone does not work
Resolder microphone
END
No
Yes
Yes
Check the reference
voltage on mic path
R418 ≒2.0V
Yes
Resolder or change C423
No
Is microphone OK?
Yes
Check U100
No
1
2

SGH-X481 Flow Chart of Troubleshooting
2-8

SGH-X481 Flow Chart of Troubleshooting
2-9
2-1-5. Speaker Part
Check the connection
status of LCD connector
CN200
There is no sound from speaker
Are there any signal at
the speaker pad on LCD
PCB?
reconnect CN200
Replace the speaker module
END
No
Yes
No
No
Yes
Check R402, R403 of
U402. Voltage is ≥1V?
1
Yes
Check U500
2

SGH-X481 Flow Chart of Troubleshooting
2-10

SGH-X481 Flow Chart of Troubleshooting
2-11
2-1-6. LCD backlight
Backlight ON "TIME"
mode in the menu?
Backlight does not work
Check conecting
between PBA and LCD
conector
Select backlight "15 sec" mode
Check FPCB
END
No
Yes
No
Check U200 pin #8 =
10V ? Check the LCD
Yes
Yes
No

SGH-X481 Flow Chart of Troubleshooting
2-12
2-2. RF
2-2-1. GSM Rx
Normal condition
catch the
channel ?
Check U900
pin 12 ≥-65
dbm ?
Check U801
pin 21,22 ≥-
65dBm ?
Yes
No
No
Check U900
pin 16 ≥-65
dbm ?
Yes
No
Yes
Check ANT, C824,C825,C904,C903
Resolder or change
CON901, C903, L903, L904, C901, C902
Resolder or change
U900
Resolder or change
F900
Resolder or change
U600
CONTINOUS RX ON
RF INPUT : 62CH
AMP : -60dbm
Check U801
pin 13 = 2.9V
Yes
Resolder or change
U100
Yes
No
No
1
2
3
4
5

SGH-X481 Flow Chart of Troubleshooting
2-13

SGH-X481 Flow Chart of Troubleshooting
2-14
2-2-2. DCS Rx
Normal condition
catch the
channel ?
Check U900
pin 12 ≥-65
dbm ?
Check U801
pin 19,20 ≥-
65dBm ?
Yes
No
No
Check U900
pin 18 ≥-65
dbm ?
Yes
No
Yes
Check ANT,C822,C823,L802
Resolder or change
CON901, C903, L903, L904, C901, C902
Resolder or change
U900
Resolder or change
F900
Resolder or change
U600
CONTINOUS RX ON
RF INPUT : 698CH
AMP : -60dbm
Check U801
pin 13 = 2.9V
Yes
Resolder or change
U100
Yes
No
No
1
2
3
4
5

SGH-X481 Flow Chart of Troubleshooting
2-15

SGH-X481 Flow Chart of Troubleshooting
2-16
2-2-3. PCS Rx
CONTINOUS RX ON
RF INPUT : 660CH
AMP : -50dbm
Normal condition
catch the
channel ?
Check ANT,C820,C821,L801
No 1
Yes
Check U900
pin 12 ≥-65
dbm ? 2
Resolder or change
CON901, C903, L903, L904, C901, C902
No
Yes
Check U900
pin 18 ≥-65
dbm ?
Resolder or change
U900
No 3
Yes
Check U801
pin 19,20 ≥-
65dBm ?
4
No Resolder or change
F900
Yes
Check U801
pin 13 = 2.9V
No Resolder or change
U100 5
Yes
Resolder or change
U600

SGH-X481 Flow Chart of Troubleshooting
2-17