lg 21FB5RB, 21FB5RG, 21FB5RGE, 21FB5RL, 21FB5RB-TH Service Manual

website:http://biz.LGservice.com e-mail:http://www.LGEservice.com/techsup.html

COLOR TV SERVICE MANUAL

CHASSIS : MC-059B

MODEL: 21FB5RB/RG/RGE/RL

MODEL: 21FB5RB/RG/RGE/RL-TH

CAUTION

BEFORE SERVICING THE CHASSIS,

READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

CONTENTS

CONTENTS.............................................................................................................	2
SAFETY PRECAUTIONS....................................................................................	3
DESCRIPTION OF CONTROLS.......................................................................	4
SPECIFICATIONS ..................................................................................................	7
ADJUSTMENT........................................................................................................	9
PRINTED CIRCUIT BOARD.............................................................................	14
BLOCK DIAGRAM...............................................................................................	15
TROUBLE SHOOTING .......................................................................................	16
EXPLODED VIEW................................................................................................	20
EXPLODED VIEW PARTS LIST .....................................................................	21
REPLACEMENT PARTS LIST .......................................................................	22

- 2 -

SAFETY PRECAUTIONS

IMPORTANT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the Schematic Diagram and Replacement Parts List.

It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards.

Do not modify the original design without permission of manufacturer.

General Guidance

An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks.

It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

Due to high vacuum and large surface area of picture tube, extreme care should be used in handling the Picture Tube. Do not lift the Picture tube by it's Neck.

X-RAY Radiation

Warning:

The source of X-RAY RADIATION in this TV receiver is the High Voltage Section and the Picture Tube.

For continued X-RAY RADIATION protection, the replacement tube must be the same type tube as specified in the Replacement Parts List.

To determine the presence of high voltage, use an accurate high impedance HV meter.

Adjust brightness, color, contrast controls to minimum. Measure the high voltage.

The meter reading should indicate

23.5 ¡	1.5KV: 14-19 inch, 26 ¡ 1.5KV: 19-21 inch,
29.0 ¡	1.5KV: 25-29 inch, 30.0 ¡ 1.5KV: 32 inch

If the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

Before returning the receiver to the customer,

always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Leakage Current Cold Check(Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc.

If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1M and 5.2M . When the exposed metal has no return path to the chassis the reading must be infinite.

An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage Current Hot Check (See below Figure) Plug the AC cord directly into the AC outlet.

Do not use a line Isolation Transformer during this check.

Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts.

Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity.

Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each exposed metallic part. Any voltage measured must not exceed 0.75 volt RMS which is corresponds to 0.5mA.

In case any measurement is out of the limits specified, there is possibility of shock hazard and the set must be checked and repaired before it is returned to the customer.

Leakage Current Hot Check circuit

AC Volt-meter

					Good Earth Ground
					such as WATER PIPE,
	To Instrument’s				CONDUIT etc.
		0.15uF
	exposed
	METALLIC PARTS

1.5 Kohm/10W

- 3 -

DESCRIPTION OF CONTROLS

					All the functions can be controlled with the remote control handset.
					Some functions can also be adjusted with the buttons on the front
					panel of the set.
					Remote control handset
					Before you use the remote control handset, please install the bat-
					teries. See the next page.
					1.	POWER
1	POWER			MUTE		switches the set on from standby or off to standby.
	1	2		3	2.	NUMBER BUTTONS
	4	5		6		switches the set on from standby or directly select a number.
2
					3.	MENU (or INDEX)
	7	8		9		selects a menu.
						selects an index page in the teletext mode (only TELETEXT
3	MENU/INDEX	0		TV/AV		models). (option)
				TV		EYE/* (option)
4					4.
				I /		switches the eye function on or off.
	EYE/	PR		II /
			(	)
					5.	D / E (Programme Up/Down)
5	VOL	OK		VOL		selects a programme or a menu item.
						switches the set on from standby.
		PR	(	)		scans programmes automatically.
	Q.			LIST		F / G (Volume Up/Down)
6	VIEW
						adjusts the volume.
	PSM	SSM/		SLEEP		adjusts menu settings.
						OK
7
	FAVOURITE					accepts your selection or displays the current mode.
8				/
		PICTURE		SOUND
					6.	Q.VIEW
9			TURBO/
						returns to the previously viewed programme.
					7. PSM (Picture Status Memory)
						recalls your preferred picture setting.
					8.	FAVOURITE
						selects a favorite programme.
					9. TURBO PICTURE / SOUND BUTTON (option)
						selects Turbo picture and sound.

- 4 -

10.MUTE

switches the sound on or off.

11.TV/AV

selects TV or AV mode.

switches the set on from standby.

12.I/II/* (option)

selects the language during dual language broadcast. (option) selects the sound output.

13.LIST

displays the programme table.

14.SLEEP

sets the sleep timer.

15.SSM/* (Sound Status Memory) (option) recalls your preferred sound setting.

16.SURROUND (º/*) (option) selects surround sound.

* : No function

COLOURED BUTTONS : These buttons are used for teletext (only TELETEXT models) or programme edit.

POWER MUTE

10

1			2				3
4			5				6
7			8				9
MENU/INDEX			0			TV/AV		11
							TV
		/			I	/	II /	12
E
EY			PR	(	)
VOL			OK				VOL
Q.			PR	(	)
							T
V	I	EW
						IS
					L			13
PSM			SSM/			SLEEP
								14
FAVOURITE							/	15
			PICTURE		SOUND			16

TURBO/

- 5 -

Front panel

7

6

AV2

VIDEO L/MONO AUDIO R

MENU OK	VOL	VIDEO L AUDIO R
		PR
ON/OFF
		AV

1 2 3 4 5 6 7 8

1.MAIN POWER (ON/OFF) switches the set on or off.

2.POWER/STANDBY INDICATOR

illuminates brightly when the set is in standby mode. dims when the set is switched on.

3.REMOTE CONTROL SENSOR

Note : Only use the supplied remote control handset. (When you use others, they’ll be not able to function.)

4.MENU

selects a menu.

5.OK

accepts your selection or displays the current mode.

F / G (Volume Up/Down)

adjusts the volume. adjusts menu settings.

D / E (Programme Up/Down) selects a programme or a menu item. switches the set on from standby.

6.AUDIO/VIDEO IN SOCKETS (AV2) (option)

Connect the audio/video out sockets of external equipment to these sockets.

7.HEADPHONE SOCKET (option)

Connect the headphone plug to this socket.

8.EYE (option)

adjusts picture according to the surrounding conditions.

9.TV/AV (option)

selects TV or AV mode.

clears the menu from the screen. switches the set on from standby.

10. (Function) (option)

selects volume, EYE (option), picture items or brief auto programme while the menus not display.

11.+ / - (D / E) (option)

adjusts the function or selects a programme. switches the set on from standby.

12.TURBO SOUND / PICTURE (option)

switches Turbo sound or Turbo picture function on or off.

Note :

a.Do not place any heavy objects (over 4Kg) on the RF/RT-21FA35 series models.

b.Shown is a simplified representation of front or side panel. Here shown may be somewhat different from your set.

- 6 -

SPECIFICATIONS

Note : Specification and others are subject to change without notice for improvement.

V Scope

This specification can be applied to all the television related to

MC-059A Chassis.

4)Specification and performance of each parts are followed each drawing and specification by part number in accordance with BOM.

5)The receiver must be operated for about 20 minutes prior to the adjustment.

V Requirement for Test

Each part is tested as below without special appointment.

					V Test Method
1) Temperature : 25 ± 5°C (77 ± 9°F), CST : 40 ± 5					1) Performance : LGE TV test method followed.
	(CST must be tested 40 ± 5°C . Humidity : 50%)				2) Demanded other specification
2) Relative Humidity : 65 ± 10%					- CCC
3) Power Voltage : Standard input Voltage (110-240V~,					- Safety : IEC60065
	50/60Hz)
	* Standard Voltage of each products is marked by models.
A General specification
	No.	Item		Specification
	1	Receiving System	PAL BG, DK, I / NTSC M (AV 3.58/ 4.43)
	2	Available Channel	VHF : E2 ~ E12
			UHF : E21 ~ E69
			CATV : S1 ~ S20
			HYPER : S21 ~ S41
	3	Input Voltage	100 - 240V~,	50/60Hz
	4	Market	China, Indonesia, Thai, Vietnam, CIS
	5	Screen Size	14 ~ 21inch (FLAT / Conventional)
	6	Aspect Ratio	4:3
	7	Display Method	CRT
	8	Tuning System	FVS
	9	Operating Environment	Temp	: 0 ~ 40 deg
			Humidity	: ~ 85 %
	10	Storage Environment	Temp	: -20 ~ 60 deg
			Humidity	: ~ 90 %

- 7 -

A Features and Function

No.		Item			Specification	Remark
1	Feature	AV Input	2		AV 1, 2	Rear1, Front1(CVBS,L,R)
		AV Output	1		Monitor out	Rear
		Earphone	1		Front
2	Key	Local Key	Power, Vol(F, G), PR(E, D), MENU, OK			7EA/ Front
			Turbo-Picture, Sound			Option
		Remocon	LG Code (NEC)
3	Channel	Auto prog.	System/ Storage/ Normal/ Turbo
		Manual	Storage/ System/ Channel/ Fine/
			Search/ Name
		Prog. edit	Copy/ Move/ Delete/ Skip
		Favorite	8 Channel
4	Picture	PSM	Dynamic/ Standard/ Mild/ Game/ User
		User Control	Contrast/ Brightness/ Color/ Sharpness
			Tint (NTSC-M Only)
5	Sound	SSM	Flat/ Music/ Movie/ Speech/ User
		Treble/ Bass	0 ~ 100
		Equalizer	100/ 400/ 1K/ 4K/ 10K
6	Timer	Clock	-- : --
		Off time	-- : -- Off(On)
		On time	-- : -- Pr 1 VOL 30 Off(On)
		Auto off	On/ Off
7	Special	Language	English/ Russia			CIS
			English/ Indonesia/ Thai/ Vietnam			East-Asia
		Input	TV/ AV1/ AV2
		Child lock	On/ Off
8	Etc.	Sleep

- 8 -

ADJUSTMENT

1. Scope of Application

These instructions are applied to MC-059B Chassis.

2.Notes

1)Because this is a cold chassis, it is not necessary to use an isolation transformer. However, operating it using a transformer between the power supply line and chassis input to prevent electric shock and to protect the test instrument.

2)Adjustment must be done in the correct order.

3)The adjustment must be performed in the circumstance of 25 ± 5°C of temperature and 65 ± 10% of relative humidity if there is no specific designation.

4)The input voltage of the receiver must keep (100-240~ ± 10%, 50/60Hz) in adjusting

5)The receiver must be operated for about 15 minutes prior to the adjustment. But adjusting on the board can be done in jig state right away.

6)Signal: The standard color signal is approved in 65±1dBuV.

3.AGC Voltage Adjustment

3-1. Necessary Instrument

Digital Multi meter : 1 set

-Max Input Current : Over 1A/ Max Input Voltage : 500Vdc

-Measurement Range : 10mV-100mVdc/ Accuracy : 0.03%

3-2. Adjustment Preparation

1)Input LG standard signal into 75Ω antenna terminal (or PAL-B/G 05CH)

2)Connect the digital multi-meter to terminal(with Hole/ J105) with AGC Check.

3-3. Adjustment

1)Select the VP 0(RF AGC) adjustment mode by pressing IN-START key on the SVC remote control.

2)After select the RF AGC using CH +/- key, adjust the multi-meter voltage to be as shown below.

- 6700MF0014A(LG INNOTEK): 2.3±0.05V, 65dBu,

TAEW-G013D - 6700PF0006B(SANYO): 2.3±0.05V, 65dBu,

115-B-A86EL

3)CAUTION

:Since the signal strength can be easily changed by the condition of signal cable, you need to check the signal strength frequently in order to prevent error.

4.Screen Voltage Adjustment

4-1. Adjustment of Screen Manually

(Using SVC Remote Control)

1)Receive the PAL(SECAM) signal into RF mode regardless of channel.

2)If you press the “ADJ’ key on LINE SVC remote control, changes to screen adjustment mode.

3)Adjust the Screen Vol. of FBT to appear Horizontal Line and adjust the Screen Vol. of FBT at disappear point Horizontal Line.(Press the Enter(A) key to exit SVC mode)

5. Purity and Convergence Adjustment

5-1. Purity Adjustment

(1)Adjustment Preparation

1)Receive Red Raster Pattern for purity adjustment.

2)Demagnetize the CPT and Cabinet with a degaussing coil.

(2)Horizontal Line Adjustment

1)Pre-adjust the static convergence (STC) with the 4 and 6pole magnet.

2)Check if the beam land at mask hole by setting two 2- pole magnets in opposite direction respectively.

3)If not, adjust 2-pole magnet so the beam as to land at mask hole accurately.

(3)Purity Adjustment

1)Adhere DY closely to CPT.

2)Receive Red Pattern and adjust the 2-Pole magnet so Red color Bar as to locate center and make the portion of Green color and Blue color same.<Fig.1>

G R B G R B <Fig. 1>

3)Make the full screen Red by pulling DY back slowly. (When adhering DY, use the electric driver of which turning force is lower than 10Kg/Cm) <Fig. 2>

G	R	B				R

<Fig. 2>

5-2. Convergency Adjustment

(1)Necessary Instrument

1)Degaussing Coil

2)Convergency fixing instrument

(2)Preliminary steps

1)Heat run over 30 minutes before adjustment.

2)Demagnetize the CPT and Cabinet by using degaussing coil.

3)Receive Cross Hatch Pattern.(EU09CH)

4)Adjust Contrast and Brightness for easy observation.

(3)Static Convergence (STC) Adjustment

1)Receive Cross Hatch Pattern(EU09CH)

2)Adjust the focus first seeing to it that the WHITE color picture quality is sharp enough.

3)Open two 4-Pole magnets until vertical Red and Blue lines are unified.

4)Rotate the 4-Pole magnets keeping the angle between two 4-Pole magnets until horizontal Red and Blue lines are unified.

5)Open two 6-Pole magnets until vertical Red and Green lines are unified.

6)Rotate the 6-Pole magnets keeping the angle between two 4-Pole magnets until horizontal Red and Blue lines are unified.

- 9 -