LG Electronics 42LN548C, 361H-ZA IC Remove/Replacement, Removal, Circuit Board Foil Repair

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IC Remove/Replacement

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the cir- cuit 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 remain- ing 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 pos- sible 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 when- ever 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 connec- tions).

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 con- nected 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.

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Contents READ THE SAFETY PRECAUTIONS IN THIS MANUAL SERVICE MANUALLED TV MODEL 42LP360H/361H 42LN548C/549CCopyright Only for training and service purposesLG Electronics. Inc. All rights reserved LGE Internal Use OnlyGeneral Guidance SAFETY PRECAUTIONSBefore returning the receiver to the customer Leakage Current Cold CheckAntenna Cold CheckElectrostatically Sensitive ES Devices SERVICING PRECAUTIONSReplacement IC Remove/ReplacementSmall-Signal Discrete Transistor Removal/Replacement Removal4. Model General Specification SPECIFICATION1. Application range 3. Test methodDVB-T Symbolrate 4.0Msymbols/s to 7.2Msymbols/sGuard IntervalBitrateMbit/s 1/4, 1/8, 1/16, 1/325.1. Component Input Y, CB/PB, CR/PR 5. Video resolutions 2D5.2. RGB Input PC - HD Model 5.3. RGB Input PC - FHD ModelPCDVI 5.3. HDMI InputPC/DTV1. Application Range ADJUSTMENT INSTRUCTION2. Designation 3. Main PCB check process3.1. ADC Process After downloading, have to adjust Tool Option again3.2. EDID Download 3.3. EDID data3.4 Function Check 4. Total Assembly line process4.1. White Balance adjustment 6. Model name & Serial number D/L 5. GND and HI-POT Test6.1. Signal Table 4.5. Outgoing condition Configuration6.3. Method & notice 7. CI+ key download7.1. Communication Prot connection 7.2. CI+ Key Download8.2. IR OUT 8. Check Commercial Features8.1. External speaker8OHM, 1W, Single-End 2. Digital TV Video TROUBLE SHOOTING GUIDE1. Check the booting Voltage 4. AV Video 3. Analog TV Video6. HDMI Video 5. RGB Video8. TV Audio 7. Audio of All iput10. RGB Audio 9. AV AudioTuner DVB- T/C BLOCK DIAGRAMS7LR2 LGE211A-T8 EXPLODED VIEW Copyright 2013 LG Electronics. Inc. All rights reserved 2013 S7LR22012 FILRE AND ELECTRICAL SHOCK HAZARDS, WHEN SERVICING IF IS SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATESVDDC NormalPowerDET FROM LIPS & POWER B/D+1.5VDDR +3.3VNormal780 mANTP-7500L IC501SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM X-RADIATION THE SYMBOL MARK OF THIS SCHEMETIC DIAGRAM INCORPORATESTHE CRITICAL COMPONENTS IN THE SYMBOL MARK OF THE SCHEMETIC CONTROL IR & LED51Pin LVDS Connector For FHD 60Hz LVDS30Pin LVDS Connector FOR FHD REVERSE10bit Change in S7LRHDMI1 HDMI EEPROMHDMI2 For CECRS - 232C RS232CRGB PC HEADPHONESIDE USB PC AUDIODDR256 S7LRDIVXMS10DDR13331GHYNIX EAN61828901SFLASH F u l l REAR COMPONENT PHONE JACKS c a r t SCART AUDIO MUTESPEAKER OUT JACK EXTSPEAKERAMPEXTSPK IC1800CI Region CI POWER ENABLE CONTROLOption name of this page CI SLOT because of Hong Kong PCMCITU2602 GP4RGLOBALTUNERBLOCKTU2603 TDSS-G101D