LG Electronics 42LA69**-Z* service manual Safety Precautions, General Guidance

Page 3

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

Copyright ©

LG Electronics. Inc. All rights reserved.

- 3 -

LGE Internal Use Only

Only for training and service purposes

 

 

Image 3
Contents LED TV Contents General Guidance Safety PrecautionsElectrostatically Sensitive ES Devices Servicing PrecautionsIC Remove/Replacement Small-Signal Discrete Transistor Removal/ReplacementCircuit Board Foil Repair Requirement for Test SpecificationModel General Specification Application range Test methodQpsk PAL-BG PAL-DKVHF, UHF DVB-TComponent Video Input Y, Pb, Pr PC mode Hdmi Input 6.1. DTV modeHdmi 1.4b 3D supported mode automatically 3D ModeHdmi Input1.3 RF Input3D supported mode manuallyRF Input 3D supported mode automatically USB Input 3D supported mode manuallyInput mode HDMI-PC Input 3D supported mode manuallyDlna Input 3D supported mode manually Component Input3D 3D supported mode manuallyDesignation Adjustment InstructionAutomatic Adjustment Application RangeCI+ Key checking method Model name & Serial number DownloadEdid Manual AdjustmentCheck the method of CI+ Key value Check the method of CI+ key valueRS232Equipment White Balance AdjustmentAdj. Command Protocol OverviewAlelf & Edge LED White balance table Adj. methodFunction test Magic Motion Remote control testWi-Fi Test Local Dimming Function CheckAudio Ship-out mode checkIn-stopGND and Internal Pressure check Tool Option selectionAfter downloading, have to adjust Tool Option again USB S/W DownloadService onlyDiagram BlockLGE Exploded View Important Safety Notice