Samsung SGH-A400 Troubleshooting

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5-1

5.Flow Chart of Troubleshooting and Circuit Diagram

5-1 SGH-A400 Power ON

N

‘POWER ON’ does not work

Y

Check the current

consumption more than

100 mA

Download again

N

Y

Check the

Battery Voltage more

than 3.3V

Charge the Battery

N

Y

Check the pin

38 of U400 is more than

3.2 V

Check to the path from CN604 to pin

38 of U400 and keypad

N

Y

U400 pin 33,28,30

= 2.8V

Change U400

N

Y

END

Y

Check the clock signal

at R105

Check the clock generation circuit

(related to U400 and OSC100)

Check the initial operation

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5-2

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

5-2 SGH-A400 Initial

N

Initial Failure

Y

Check the “Reset_B” signal at the pin 6 of

U8016 is “High”

Check the U100 (IA)

N

Y

Check the pin 10

of U400 is “High”

Check the U201 (M46)

N

Y

Check the pin 11 of U400

is “High”

Check the U400 (PMIC)

Y

Check the connections and initialization using Factory

Test Program

END

Y

Check LCD connector CN601,

and resolder bridge

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5-3

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

5-3 SGH-A400 Sim Part

Phone can’t access SIM card

Y

N

Y

Check the pin 1, 5 of

CN400. voltage is 2.8V ?

Check the SIM related circuit of the U400

N

Y

Check the SIM

connector’s CN400

Connection to

SIM card

Resolder CN400

END

Y

Check the circuit around U515

(Serial EEPROM) and data stored in it

VSYN

VCCD

Sim_Dat

Sim_En

Sim_Reset

VRF

VOsc

VCCA1

PMIC_RESET

C410 150PF

100

R410

Clk_Rqst

S_Dat S_Clk

Sim_Clk

CN400

1

U400

VCCD

VTIC

VSIM

VSW1

24

25

VSW2

VCCD

ISENP

100K

R404

ZD402

R407

4.7K

VBAT

10

G

ISENN

VCCD

R409

321

VSIM

U8016-1

4

1

2

8

7

4.7K

VOUT_1A30VOUT_2

VOUT_3 28

31

VOUT_4A

VOUT_4B

32

29

VOUT_5

VOUT_6

27

43

VOUT_7

VOUT_8

48

VREF_CAP

44

VSUB_P

20

17

18

SIM_CLK_M46

SIM_DATA_CARD15SIM_DATA_M46

16

14

SIM_ENABLE21SIM_RST_CARD

SIM_RST_M46

22

VBAT1

37

38

VBAT2

VBOOST

39

VOUT1B

34

33

35

NC1

NC2

36

NC3

4

NC4

26

9

PMIC_INTERRUPT

45

POWER_KEY

POWER_ON_RESET

11

RESET_B

2

3

RSS_CLOCK

RSS_DATA

1

SIM_CLK_CARD

6 7

ENABLE_2 ENABLE_3

8

GND1

23

12

GND2

5

GND3

49

GND4

GND5

50 51

GND6

GND7

52

GND_SENSE

19

ALARM_IN

46

13

BOOST_ENABLE

42

BOOST_PULSE41BOOT_SENSE

BOOT_VDD

40

10

CLOCK_REQUEST

47

DTR_IN

ENABLE_1

2

2 3

3

44 55

66

G78GG

9

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5-4

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

Abnormal charging part

Y

N

Y

Check

the pin 17, 18 of CN604-1

is around 5V

Replace TA

N

Y

Check the pin 2 of U8021

is “Low”

Check the U201

using Factory Test Program

N

Y

Check the

pin 5, 6 of U8021 is more

than 0.5V

Resolder R648, R651, R646

N

Y

Check the

Voltage of pin 5 of

U605 is between 3.2 V

and 4.2 V

Change U605

END

5-4 SGH-A400 Charging Part

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5-5

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

Mic-

C113

Mic+

Mic_Bias

22PF

1.1K

R103 330

C108 33UF

R104

C111 22PF

C116

C115 47NF

C112 47NF

1.1K

R107

33PF

5-5 SGH-A400 Microphone Part

Micro Phone does not work

Y

N

Y

check the connection

from MIC600

Change MIC600

N

Y

Audio loopback

is enabled by board test

program.

R104, R107 2.2 V

Resolder R104, R107, R103

END

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5-6

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

Speaker does not work

Y

N

Y

Check the

connection from CN601

to LCD Module

Replace Flexible PCB

N

Y

Check the

voltage on the speaker

line lands on LCD

Module

Change the LCD Module

N

Y

Is Speaker working ?

Replace the Speaker or resolder Speaker

END

5-6 SGH-A400 Speaker Part

Check the connection between CN601

and LCD Module connector

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5-7

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

5-7 SGH-A400 Key Data Input

Check initial operation

Y

N

Y

Check the

pin 1, 3, 4, of CN602 is

“High”

Check the M46(U201)

N

Y

When one of the keys is

pushed, one of pin [5:12] of

CN602 is “High”

Replace the key PCB

END

Check the connection between

CN602 and Keypad.

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5-8

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

5-8 SGH-A400 Ring Indicator

Ring Indicator does not work

Y

N

Y

Check the Q203 pin 2 is

“High”

Check M46(U201)

by Factory Test Program

N

Y

Check the Q203 pin 3 is

“Low”

Replace Q203

N

Y

CN602 pin 14 = “L” ?

Resolder CN602

N

Y

Key PCB is OK ?

Replace the key PCB

END

Check the connection between

CN602 and Keypad.

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5-9

SGH-A400 Flow Chart of Troubleshooting and Circuit Diagram

5-9 SGH-A400 Back Light

Backlight does not work

Y

N

Y

Backlight

“ON” mode in

the menu ?

Select backlight “ON” mode

N

Y

CN601 pin 3 = “High” ?

Check M46(U201)

using Factory Test Program

N

Y

Check the

connection from CN601

to LCD Module

Replace flexible PCB

N

Y

LCD backlight on ?

Replace LCD Module

END

Check the connection between

CN601 and LCD Module.