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Electrostatic Damage (ESD):
Semiconductor devices are easily damaged by electrostatic discharge. Many of the procedures
detailed in this manual involve disassembly of the equipment and therefore handling of the printed
circuit boards.
To protect these devices from ESD a wrist strap connected to ground must be worn.
In addition to this the work surface must be covered with an anti-electrostatic mat, which should also
be grounded.
If printed circuit boards are to be stored without being re-assembled into their equipment, then they
must be kept in an anti-electrostatic bag.
Grounding:
Each piece of test equipment should be electrically grounded. A third (grounding) pin is provided as a
safety feature. Ensure that the electrical outlet also contains this feature.
Cosmetic Protection during Repair Work:
Always ensure that the working surface is kept clean and free from abrasive materials.
The LCD is very susceptible to scratches and damage. It should be covered with clear adhesive vinyl
while the equipment is disassembled.
Storage of Faulty Components:
Any components that are replaced due to failure should be kept safely in an antielectrostatic container.
NEC's Quality or Research & Development Departments may require them to make quality and
reliability investigations.
No Fault Found Equipment:
In some cases the reported symptom may not be apparent. You may subject the equipment to a
controlled amount of stress, vibration and temperature variation to see if the fault occurs.
Care should be taken not to apply excessive stress or vibration or extreme temperature variations as
further faults may develop.
Soldering and Disordering:
The solder used is only Pb-free.
Fast, accurate and high quality soldering is required to minimise the risk of heat damage to the
electronic components. It is necessary to adjust the temperature of soldering tip to 330 degrees or
less. The soldering tip should not be in contact with components or PCB tracks for longer than 4
seconds (average). This time depends on temperature conditions of parts.
Heat the pad on the PCB and the lead, quickly apply solder, remove heat and cool. After soldering is
complete, ensure that all solder joints are of good quality - no dry joints, solder bridges, cracks or
excess solder. The majority of chip components are machine mounted using solder paste. Removal of
the solder is not sufficient for chip component removal. Each solder point must be heated
simultaneously and quickly (to prevent component and PCB damage). When the solder has melted,
remove the component with tweezers.
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
2. Precautions for Repair Work
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LGE Internal Use Only
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