LG 32LX770M Schematic

Internal Use Only

LED TV

SERVICE MANUAL

CHASSIS : LA5GI

MODEL : 32LX770M 32LX770M-UA

CAUTION

BEFORE SERVICING THE CHASSIS,

READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

P/NO : MFL69373706 (1512-REV00)	Printed in Korea

CONTENTS

CONTENTS ..............................................................................................	2
SAFETY PRECAUTIONS .........................................................................	3
SERVICING PRECAUTIONS....................................................................	4
SPECIFICATION.........................................................................................	6
ADJUSTMENT INSTRUCTION.................................................................	8
TROUBLE SHOOTING GUIDE...............................................................	19
BLOCK DIAGRAM..................................................................................	25
EXPLODED VIEW ..................................................................................	26

Copyright ©	LG Electronics. Inc. All rights reserved.	- 2 -	LGE Internal Use Only
Only for training and service purposes

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 Exploded View.

It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent 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 1 W), keep the resistor 10 mm away from PCB.

Keep wires away from high voltage or high temperature parts.

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 1 MΩ and 5.2 MΩ.

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 1.5 K / 10 watt resistor in parallel with a 0.15 uF 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 0.5 mA.

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

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Only for training and service purposes

SERVICING PRECAUTIONS

CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the SAFETY PRECAUTIONS on page 3 of this publication.

NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions on page 3 of this publication, always follow the safety precautions. Remember: Safety First.

General Servicing Precautions

1.Always unplug the receiver AC power cord from the AC power source before;

a.Removing or reinstalling any component, circuit board module or any other receiver assembly.

b.Disconnecting or reconnecting any receiver electrical plug or other electrical connection.

c.Connecting a test substitute in parallel with an electrolytic capacitor in the receiver.

CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard.

2.Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".

3.Do not spray chemicals on or near this receiver or any of its assemblies.

4.Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the contacts with a pipe cleaner, cotton-tipped stick or comparable non-abrasive applicator; 10 % (by volume) Acetone and 90 % (by volume) isopropyl alcohol (90 % - 99 % strength)

CAUTION: This is a flammable mixture.

Unless specified otherwise in this service manual, lubrication of contacts in not required.

5.Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.

6.Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.

7.Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead.

Always remove the test receiver ground lead last.

8.Use with this receiver only the test fixtures specified in this service manual.

CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and semiconductor “chip” components. The following techniques should be used to help reduce the incidence of component damage caused by static by static electricity.

1.Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed to prevent potential shock reasons prior to applying power to the unit under test.

2.After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3.Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4.Use only an anti-static type solder removal device. Some solder removal devices not classified as “anti-static” can generate electrical charges sufficient to damage ES devices.

5.Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.

6.Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive material).

7.Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed.

CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8.Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES device.)

General Soldering Guidelines

1.Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within the range or 500 °F to 600 °F.

2.Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.

3.Keep the soldering iron tip clean and well tinned.

4.Thoroughly clean the surfaces to be soldered. Use a mall wirebristle (0.5 inch, or 1.25 cm) brush with a metal handle.

Do not use freon-propelled spray-on cleaners.

5.Use the following unsoldering technique

a.Allow the soldering iron tip to reach normal temperature. (500 °F to 600 °F)

b.Heat the component lead until the solder melts.

c.Quickly draw the melted solder with an anti-static, suctiontype solder removal device or with solder braid. CAUTION: Work quickly to avoid overheating the circuit board printed foil.

6.Use the following soldering technique.

a.Allow the soldering iron tip to reach a normal temperature (500 °F to 600 °F)

b.First, hold the soldering iron tip and solder the strand against the component lead until the solder melts.

c.Quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there only until the solder flows onto and around both the component lead and the foil.

CAUTION: Work quickly to avoid overheating the circuit board printed foil.

d.Closely inspect the solder area and remove any excess or splashed solder with a small wire-bristle brush.

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Only for training and service purposes

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

Removal

1.Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts.

2.Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing

the IC.

Replacement

1.Carefully insert the replacement IC in the circuit board.

2.Carefully bend each IC lead against the circuit foil pad and solder it.

3.Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor

Removal/Replacement

1.Remove the defective transistor by clipping its leads as close as possible to the component body.

2.Bend into a "U" shape the end of each of three leads remaining on the circuit board.

3.Bend into a "U" shape the replacement transistor leads.

4.Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection.

Power Output, Transistor Device

Removal/Replacement

1.Heat and remove all solder from around the transistor leads.

2.Remove the heat sink mounting screw (if so equipped).

3.Carefully remove the transistor from the heat sink of the circuit board.

4.Insert new transistor in the circuit board.

5.Solder each transistor lead, and clip off excess lead.

6.Replace heat sink.

Diode Removal/Replacement

1.Remove defective diode by clipping its leads as close as possible to diode body.

2.Bend the two remaining leads perpendicular y to the circuit board.

3.Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.

4.Securely crimp each connection and solder it.

5.Inspect (on the circuit board copper side) the solder joints of the two "original" leads. If they are not shiny, reheat them and if necessary, apply additional solder.

Fuse and Conventional Resistor

Removal/Replacement

1.Clip each fuse or resistor lead at top of the circuit board hollow stake.

2.Securely crimp the leads of replacement component around notch at stake top.

3.Solder the connections.

CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to prevent excessive component temperatures.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board. (Use this technique only on IC connections).

1.Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).

2.carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.

3.Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.

4.Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

At Other Connections

Use the following technique to repair the defective copper pattern at connections other than IC Pins. This technique involves the installation of a jumper wire on the component side of the circuit board.

1.Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous condition will not exist if the jumper wire opens.

2.Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly connected to the affected copper pattern.

3.Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead of the nearest component on the other side.

Carefully crimp and solder the connections.

CAUTION: Be sure the insulated jumper wire is dressed so the it does not touch components or sharp edges.

Copyright ©	LG Electronics. Inc. All rights reserved.	- 5 -	LGE Internal Use Only
Only for training and service purposes

SPECIFICATION

NOTE : Specifications and others are subject to change without notice for improvement.

1. Application range

This specification is applied to the LED TV used LA5GI chassis.

2. Test condition

Each part is tested as below without special appointment.

(1)Temperature: 25 °C ± 5 °C, CST: 40 °C ± 2 °C

(2)Relative Humidity: 65 % ± 10 %

(3)Power Voltage

:Standard input voltage (AC 100-240 V~, 50/60 Hz)

*Standard Voltage of each products is marked by models.

(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 5 minutes prior to the adjustment.

3.Test method

(1)Performance: LGE TV test method followed

(2)Demanded other specification

-Safety : UL, CSA, IEC specification

-EMC: FCC, ICES, IEC specification

-Wireless : WirelessHD Specification (Option)

4. General Specification

No	Item		Specification	Result	Remark
1	Receiving System	ATSC / NTSC-M / 64 & 256 QAM
2	Available Channel	1)	VHF : 02~13
		2)	UHF : 14~69
		3)	DTV : 02-69
		4)	CATV : 01~135
		5) CADTV : 01~135
3	Input Voltage	AC 100 ~ 240V 50/60Hz			Mark : 110V, 60Hz (N.America)
4	Market	NORTH AMERICA
5	Screen Size	32/43/55 inches
6	Aspect Ratio	16:9
7	Tuning System	FS
8	Module	LC320DUE-FHA3		LGD	32LX770M-UA
		LC430EUE-FHM3		LGD	43LX770M-UA
		LC550EUE-FHM3		LGD	55LX770M-UA
9	Operating Environment	1) Temp : 0 ~ 40 deg
		2)	Humidity : ~ 80 %
10	Storage Environment	1) Temp : -20 ~ 60 deg
		2)	Humidity : ~ 85 %

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Only for training and service purposes

5. Supported video resolutions

5.1. HDMI Input (PC/DTV)

No.	Resolution	H-freq(kHz)	V-freq.(kHz)	Pixel clock(MHz)	Proposed
	PC				DDC
1	640*350	31.46	70.09	25.17	EGA	X
2	720*400	31.46	70.08	28.32	DOS	O
3	640*480	31.46	59.94	25.17	VESA(VGA)	O
4	800*600	37.87	60.31	40.00	VESA(SVGA)	O
5	1024*768	48.36	60.00	65.00	VESA(XGA)	O
6	1152*864	54.34	60.05	80.00	VESA	O
7	1280*1024	63.98	60.02	108.00	VESA (SXGA)	X
8	1360*768	47.71	60.01	85.50	VESA (WXGA)	O
9	1920*1080	67.50	60.00	148.5	HDTV 1080P	O
	DTV
1	640*480p	31.46	59.94	25.17	SDTV 480P
2	640*480p	31.50	60.00	25.20	SDTV 480P
3	720*480p	31.47	59.94	27.00	SDTV 480P
4	720*480p	31.50	60.00	27.02	SDTV 480P
5	1280*720p	44.96	59.94	74.17	HDTV 720P
6	1280*720p	45.00	60.00	74.25	HDTV 720P
7	1920*1080i	33.72	59.94	74.17	HDTV 1080I
8	1920*1080i	33.75	60.00	74.25	HDTV 1080I
9	1920*1080p	26.97	23.97	74.17	HDTV 1080P
10	1920*1080p	27.00	24.00	74.25	HDTV 1080P
11	1920*1080p	33.71	29.97	74.17	HDTV 1080P
12	1920*1080p	33.75	30.00	74.25	HDTV 1080P
13	1920*1080p	67.43	59.94	148.35	HDTV 1080P
14	1920*1080p	67.50	60.00	148.50	HDTV 1080P

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ADJUSTMENT INSTRUCTION

1. Application

This spec. sheet applies to LA5GI Chassis applied LED TV all models manufactured in TV factory

2.Specification

(1)Because this is not a hot chassis, it is not necessary to use an isolation transformer. However, the use of isolation transformer will help protect test instrument.

(2)Adjustment must be done in the correct order.

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

(4)The input voltage of the receiver must keep 100~240V, 50/60Hz

(5)At first Worker must turn on the SET by using Power Only key.

(6)The receiver must be operated for about 5 minutes prior to the adjustment when module is in the circumstance of over 15 ºC

In case of keeping module is in the circumstance of 0°C, it should be placed in the circumstance of above 15°C for 2 hours

In case of keeping module is in the circumstance of below -20°C, it should be placed in the circumstance of above 15°C for 3 hours.

Caution

When still image is displayed for a period of 20 minutes or longer (especially where W/B scale is strong.

Digital pattern 13ch and/or Cross hatch pattern 09ch), there can some afterimage in the black level area

3. Adjustment items

3.1.Main PCBA Adjustments

(1)ADC adjustment: Component 480i, 1080p

(2)EDID downloads for HDMI

* Remark

Above adjustment items can be also performed in Final Assembly if needed. Adjustment items in both PCBA and final assembly stages can be checked by using the INSTART Menu -> 1.ADJUST CHECK.

3.2. Final assembly adjustment

▪White Balance adjustment

▪RS-232C functionality check

▪Factory Option setting per destination

▪Ship-out mode setting (In-Stop)

▪GND and HI-POT test

3.3. Appendix

▪Tool option menu, USB Download (S/W Update, Option and

Service only)

▪Manual adjustment for ADC calibration and White balance

▪Shipment conditions, Channel pre-set

4. MAIN PCBA Adjustments

4.1. ADC Calibration

-An ADC calibration is not necessary because MAIN SoC (LGExxxx) is already calibrated from IC Maker

4.2.MAC Address, ESN Key and Widevine Key, DTCP Key, HDCP1.4, HDCP2.0

download

4.2.1. Equipment & Condition

(1) Play file: keydownload.exe

4.2.2. Communication Port connection

(1)Key Write: Com 1,2,3,4 and 115200 (Baudrate)

(2)Barcode: Com 1,2,3,4 and 9600 (Baudrate)

4.2.3. Download process

(1)Select the download items.

(2)Mode check: Online Only

(3)Check the test process

-US, Canada models: DETECT -> MAC_WRITE -> WIDEVINE_WRITE

(4)Play : START

(5)Check of result: Ready, Test, OK or NG

(6)Printer out (MAC Address Label)

4.2.4. Communication Port connection

(1)Connect: PCBA Jig -> RS-232C Port == PC -> RS-232C Port

4.2.5. Download (**ESN Key : 15Y_CS_M14+)

(1)US, Canada models (15Y LCD TV + MAC + Widevine + ESN Key + DTCP Key + HDCP1.4 and HDCP2.0)

4.2.6. Inspection

- In INSTART menu, check these keys.

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(2)Mexico models (15Y LCD TV + MAC + Widevine + ESN Key + HDCP1.4 and HDCP2.0)

4.2.6. Inspection

- In INSTART menu, check these keys.

4.3. LAN Inspection

4.3.1. Equipment & Condition

▪ Each other connection to LAN Port of IP Hub and Jig

4.3.2. LAN inspection solution

▪LAN Port connection with PCB

▪Network setting at MENU Mode of TV (Installer Menu -> 119

-> 253 -> Menu)

▪setting automatic IP

▪Setting state confirmation

-If automatic setting is finished, you confirm IP and MAC Address.

4.4. LAN PORT INSPECTION(PING TEST)

4.4.1. Equipment setting

(1)Play the LAN Port Test PROGRAM.

(2)Input IP set up for an inspection to Test Program. *IP Number : 12.12.2.2

Connect SET → LAN port == PC → LAN Port

SET PC

4.4.2. LAN PORT inspection(PING TEST)

(1)Play the LAN Port Test Program.

(2)Connect each other LAN Port Jack.

(3)Play Test (F9) button and confirm OK Message.

(4)Remove LAN cable.

4.5.Model name & Serial number Download

4.5.1. Model name & Serial number D/L

▪Press "Power on" key of service remote control. (Baud rate : 115200 bps)

▪Connect RS-232C Signal to USB Cable to USB.

▪Write Serial number by use USB port.

▪Must check the serial number at Instart menu.

4.5.2. Method & notice

(1)Serial number D/L is using of scan equipment.

(2)Setting of scan equipment operated by Manufacturing Technology Group.

(3)Serial number D/L must be conformed when it is produced in production line, because serial number D/L is mandatory by D-book 4.0.

*Manual Download (Model Name and Serial Number)

If the TV set is downloaded by OTA or service man, sometimes model name or serial number is initialized.(Not always)

It is impossible to download by bar code scan, so It need Manual download.

1)Press the "Instart" key of Adjustment remote control.

2)Go to the menu "16.Model Number D/L" like below photo.

3)Input the Factory model name or Serial number like photo.

4)Check the model name Instart menu. → Factory name displayed.

5)Check the Diagnostics.(DTV country only) → Buyer model displayed.

4.6. EDID Download

4.6.1 Overview

▪It is a VESA regulation. A PC or a MNT will display an optimal resolution through information sharing without any necessity of user input. It is a realization of “Plug and Play”.

4.6.2 Equipment

▪Since embedded EDID data is used, EDID download JIG,

HDMI cable and D-sub cable are not need.

▪Adjust remocon

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