4.2 RX Trouble. LG KG291, KG290

4.2 RX Trouble

CHECKING FLOW

START

HP8960 : Test mode

62 CH, 7 level setting (TCH)

62CH, -60dBm setting (BCCH)

Spectrum analyzer setting

Oscilloscope setting

(1) Check

Crystal Circuit

(2) Check

Mobile SW &FEM

(3) Check

RX I/Q Signal

Re-download SW or

Do calibration again

4. TROUBLE SHOOTING

Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

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4. TROUBLE SHOOTING

(1) Checking Crystal Circuit

TEST POINT

C547

R520

X500

CIRCUIT

C543

1000p

CHECKING FLOW

26 MHzO.K?

Yes Crystal Circuit is OK

Change X500

2V75_VVCXO

U502

2

VCC

5

GND

3

4

R520

1M

C547

2.2u

26M_DBB

WAVEFORM

LGE Internal Use Only

Graph 4.2.1(a)

- 58 -

Graph 4.2.1(b)

Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

4. TROUBLE SHOOTING

(2) Checking Mobile SW & FEM

TEST POINT

RF 600.ANT

RF 600.RF

Vctrl 1

Vctrl 2

Vctrl 3

FL500

RF600

Vdd (C534)

Vdd (C535)

CIRCUIT

TP500 TP502 TP501

R590 NA

RF-600

SW500

G1 G2

NA R505

C517

22p

2V75_VVCXO

FL500

YGHF-S006T

10

9

7

5

4

2

GND6

GND5

GND4

GND3

GND2

GND1

20

21

22

3

VCTRL3

VCTRL2

VCTRL1

VDD

C534

39p

C535

0.1u

11

TX2G

TX1G

8

6

PCS_RX+

PCS_RX-

DCS_RX+

DCS_RX-

EGSM_RX+

EGSM_RX-

NC2

NC1

13

12

15

14

17

16

19

18

ANT_SW1

ANT_SW2

ANT_SW3

C544

39p

C545

39p

C546

39p

Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

- 59 -

WAVEFORM

EGSM RX

Vctrl 1

Vctrl 2

Vctrl 3

Graph 4.2.2 FEM Control Signal

LGE Internal Use Only

4. TROUBLE SHOOTING

CHECKING FLOW

For these 2 test case,

No Call connection is needed

Check RF600 Pin ANT,RF with RF Cable connected.

Check RF600 Pin ANT,RF with No RF Cable Connected

Open

Yes

Short

Yes

Check C544,C545,C546

Check whether Ant SW

Set as RX mode

Refer to Table 4.2.2

Check Vctrl 1,2,3 & Vdd

Yes

No

No

No

Changing RF 600

Changing RF 600

Changing the Board.

Check RF Level of

FL500.16(for EGSM) &

FL500.14&12(for DCS&PCS)

Pin 16 : ~ -62dBm

Pin 14 & 12 : ~ -63dBm

Yes

Ant SW & Mobile SW is OK

See next Page to check

Rx I/Q Signal

No Changing FL500

For this RF Level test case,

RX Stand alone Mode is needed refer to chapter 10

RX Mode

Vctrl 1

Vctrl 1

Vctrl 3

EGSM

Off

On

Off

Table 4.2.2

DCS

Off

Off

On

PCS

Off

Off

Off

LGE Internal Use Only - 60 Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

4. TROUBLE SHOOTING

(3) Checking RX I/Q

TEST POINT

C514

C541

U501

Figure 4.2.3

WAVEFORM

CIRCUIT

C514

39p

C519

0.1u

0.15MM

25

26

27

28

29

30

31

32

RX1900B

RX1900

RX1800B

RX1800

RX900B

RX900

RX850B

RX850

33

GND

U501

AD6548

VLDO2

VLDO1

VBAT

VDD

VCC_TXVCO

TXOP_HI

TXOP_LO

VLDO3

16

15

14

13

12

11

10

9

QP

QN

C541

39p

IP

IN

Graph 4.2.3

CHECKING FLOW

Check C514, C541.

Check if there is any

Major difference

Refer to graph 4.2.3

Similar?

Yes

Redownload software and calibration again

Replace U501

Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

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LGE Internal Use Only