Samsung STH-N375 User manual

SERVICE
TDMA MOBILE
TELEPHONE
STH-N375
Manual
TDMA MOBILE TELEPHONE CONTENTS
1. Trouble Shooting
2. Electrical Parts List
3. Exploded Views and Parts List
4. Block Diagrams
5. PCB Diagrams
6. Circuit Description &
Circuit Diagrams

©Samsung Electronics Co.,Ltd. May. 2002
Printed in Korea.
Code No.: GH68-02790A
BASIC.
ELECTRONICS

SAMSUNG Proprietary-Contents may change without notice
1-1
1. STH-N375 Trouble Shooting
1. Baseband Section
1-1. Program No Running
N
Need to check
Q107, Q106
N
N
Need to check
U110, U111, U206
N
Need to replace
Memory(U202)
N
Need to check TCXO OSC302
& neighbor part
Press END
Key
Y
Y
Y
Y
Y
Y
ON_SW=H
VBAT>3.2V
VCTCXO_IN=14.4 MHz
Memory (U202)
control signal
OK?
VCC=3.0V
V_VCTCXO=3.0V
RESET=3.0V
IVCC=2.2V
GBOOT_DI=H
Program Running
VCC, ADD(0:21), DATA(0:15),
FLASH_CS, SRAM_CS, UBE,
MEMOEB, MEMWEB
N
ON_SW=H
Need to check
Key Mat Need to check
Battery

N
N
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1-2
STH-N375 Trouble Shooting
1-2. Abnormal LCD Module, Vibrator & Speaker Operation
Y
N
Need to check
CN202-1
Need to check
U312 & neighbor part
N
Need to check
R125, 126
Y
Y
LCD Control
Signal OK?
Y
Y
BACKLIGHT=H
Y
VCC, ADD(2), DATA(0:7),
DISPLAY_CS, RESET
LCD Display Running
Send Command Back Light enable
Y
N
Need to check
R216 & U205
Y
LCD Display Running
Back lingt Running
Send Command Vibrator enable
Need to check
Q109, R130, R162, R163, R164
START
Y
Y
N
Need to check
U101_77,79
Y
LCD Display Running
Back lingt Running
Vibrator Running
Send Command Main Audio Receiver Path ON
Send Command Audio tone generator ON
1
VIBRATOR=H
Vibrator Run
OK?
SPK+,SPK- Signal
OK?
LED Back light
OK?
Y
N
Replace U101
Good
Speaker Output
OK?

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1-3
STH-N375 Trouble Shooting
1-3. Abnormal Buzzer operation
N
Need to check
Q207, D201, U101
START
Y
Y
Send Command Ringer Path ON
Send Command tone generator ON
N
Replace AU201
Y
Y
Buzzer Sound Output
OK?
RINGER(U101_1)
Signal OK?
Buzzer Operation
Good

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1-4
STH-N375 Trouble Shooting
1-4. Abnormal external Ear_Mic Jack operation
START
Y
Y
Hock Up Ear_Mic Phone in the Jack(CN101)
Send Command MIC_BIAS_EN enable
Send Command AMP_EN enable
N
Need to check U106
neighbor parts
Y
HS_SENSE=H
N
Need to check U106
neighbor parts
Y
Y
SEND_END=H
Press Button on the Ear-Jack
Ear_Mic phone
Operation Good

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1-5
STH-N375 Trouble Shooting
2. RF Section
2-1. Call processing and Online Test
N
DONE
START
Y
Y
Normal SVC?
Check RX path
N
Y
Set up Call
OK?
Check TX path
N
Y
Measure
SINAD/BER
Good?
Check RX path
N
YCheck TX path
Measure
Tx Power
Good?

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1-6
STH-N375 Trouble Shooting
2-2. Receiver Section (Offline test)
1
Y
Y
N
Need to check
U105, Q102
Y
N
Need to check
U306, C349
F303_2=-52dBm
N
Need to check
F302 & neighbor parts
Y
RF_BAND=L, RX_BAT=H
PLL_ON=H, PON_LC=H
VCTCXO_PC=H, IF_ON=H
PON_VRF3=H
set up 8920B basestation for RX test
Set Base station RX Lev=-50 dBm
Send Command Cell band selection
Send Command RX path ON
Send Command channel selecton
START
N
Y
V_LNA_CELL=H
U105_1=H
Q102_3=H
Need to check
U300 & neighbor parts
2
U301_45=-39.5dBm
N
Need to check
C324, F303
F303_3, U300_8
=-55dBm
F302_2=-36.0dBm
Y

SAMSUNG Proprietary-Contents may change without notice
1-7
STH-N375 Trouble Shooting
2
N
N
AMPSTDMA
N
Replace U301
Replace
F301
Need to check
OSC301, neighbor parts
& U301_1,2,3
Need to check
U105 & neighbor parts
N
Y
Y
Y
Y
YRF local check
U301_48 Lev=-6dBm
Freq=adjusted freq?
1
U301_41 Lev=-24.5dBm
Freq=130.05MHz
U301_34 Lev=-28.0dBm
Freq=130.05MHz
Need to check
U301, L301, C304, C306, R301
YReplace F300 or
Need to check R302, R303, C303
U301_25 Lev=-18.0dBm
Freq=450kHz
MODE
U301_40, 42=3.0V
43
N
U301_37 Lev=-13.0dBm
Freq=450kHz
N

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1-8
STH-N375 Trouble Shooting
N
Replace U301
Case TDMA mode:
setup basestation for RX test
Amplitude:-50dBm
3
U301_9, 10, 11, 12
measure I/Q
Quarature wave N
Need to check U301 &
Quad LC Tank circuit
(L303, C315, C316,
C317, R307)
PON_LD=H
Case AMPS mode:
setup basestation for RX test
Audio Freq gen : 1004Hz
FM deviation : 2.9kHz
4
Y Y
Y
U301_16 DEMOD
(sinusoidal wave)
Vp-p=240mV
Freq=1004Hz
N
Need to check U301 &
R326, R320, C352, C127
U101_52 DEMOD
(sinusoidal wave)
MAX Vp-p=1.4V
Freq=1004Hz
N
Replace U203
Y
U101_40 BBCLK=
6.2208MHz or 4.096NHz or
5.12MHz
N
Replace U203
Y
U101_32RX_CLK=
BBCLK/2 or
BBCLK/8
N
Replace U203
Y
U101_31 RX_SYNC=
BBCLK/32 or
BBCLK/128
N
Replace U203
Y
U101_31 RX_DATA=
serial data
DONE