LG G5200 Service Manual Trouble Shooting

4. TROUBLE SHOOTING

4.TROUBLE SHOOTING

4.1RF Components

SW401

U405

U401

U407

U408

U411

U414

U413

RF components

N401

N409

U412

Y401

Reference	Description	Reference	Description
U401	AND Gate	U412	APC IC
U405	Antenna Switch	U413	Inverter
U407	DCS RF SAW Filter	U414	LDO
U408	GSM RF SAW Filter	SW401	Mobile Switch
U409	PAM	Y401	TXVCO
U411	RF Main Chip	N401	Coupler

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4. TROUBLE SHOOTING

RX Check Area

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4. TROUBLE SHOOTING

4.1-1 Checking Regulator Circuit

U414.1 U414.6

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4. TROUBLE SHOOTING

4.1-2 Checking VCTCXO Circuit

Y401.3

Y401.4

Graph 4-1. VCTCXO 13MHz

Graph 4-2. VCTCXO 2.7V

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4. TROUBLE SHOOTING

4.1-3 Checking Control Signal

TP409(LE) TP4043(RXEN)

TP407(Data) TP408(Clock)

Graph 4-3. RF Control Signal

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4. TROUBLE SHOOTING

4-1-4 Checking Ant SW & Mobile SW

U405.10 U405.2

SW401.2

U401.1

R405

U401.6

SW401.1 U405.11 U405.1

Table 4-1. ANT SW Control Logic

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4. TROUBLE SHOOTING

Graph 4-4. ANT SW Control

GSM. DCS RX Mode

Graph 4-5. Dual AND Gate input

For GSM RX Mode

Graph 4-6. Dual AND Gate input

For DCS RX Mode

Table 4-2. ANT SW Control Logic

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4. TROUBLE SHOOTING

4-1-5 Checking Saw Filter Circuit

U407.3 U407.1 U408.3 U408.1

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4. TROUBLE SHOOTING

4-1-6 Checking RX IQ

RXIN RXQN

RXIP RXQP

Graph 4-7. RX IQ Signal		Graph 4-8. RX I Signal (Extended)

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4. TROUBLE SHOOTING

4.2 Tx Trouble

6

5

1

3

4 2

Rx Check Area

3

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4. TROUBLE SHOOTING

4-2-1 Checking Regulator Circuit

If you already Check this point while checking RX part, You can Skip this Test

U414.1

U414. 2

U414.6

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4. TROUBLE SHOOTING

4-2-2 Checking VCTCXO Circuit

If you already Check this point while checking RX part, You can Skip this Test

Y401. 3

Y401. 4

Graph 4-9. VCTCXO 13MHz

Graph 4-10. VCTCXO 2.7V

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4. TROUBLE SHOOTING

4-2-3 Checking Control Signal.

Graph 4-11. RF Control Signal

Graph 4-12. TXEN, TXRAMP, TXPA

TP409(LE)

				TXEN
				(R425)
			TXPA	TXRAMP
	TP407(Data)			(R427)
		TP408(Clock)	(R405)

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4. TROUBLE SHOOTING

4-2-4 Checking TX IQ

TXQN

C463

100P

TXQP

TXIN

C464

100P

TXIP

TXQN TXIN

TXQP TXIP

Graph 4-13. TX IQ Signal

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4. TROUBLE SHOOTING

4-2-5 Checking RF TX Level

N401. 3

U409. 1

N401. 1

R407

L405

R411

L408

C432

U409. 8

U412. 1

R472

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4. TROUBLE SHOOTING

4-2-6 Checking Ant SW & Mobile SW

SW401. 2

U405. 8

U405. 5

U405. 3

U401. 1

R405

U401. 6

SW401. 1	U405. 11	U405. 2

Table 4-1. ANT SW Control Logic

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4. TROUBLE SHOOTING

4-2-6 Checking Ant SW & Mobile SW

Graph 4-14. ANT SW Control	Graph 4-15. ANT SW Control
DCS TX Mode	GSM TX Mode

Graph 4-16.Dual AND Gate input			Graph 4-17.Dual AND Gate input
For DCS TX Mode			For GSM TX Mode

Table 4-3. ANT SW Control Logic

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4. TROUBLE SHOOTING

4-2-7 Receiver RF Level

-60dBm

-60dBm

: CH.62,

:CH.699,

GSM

DCS

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