LG 42PW350 - Basic Troubleshooting Steps; Troubleshooting Methodology

Basic Troubleshooting Steps
Define, Localize, Isolate and Correct
Define,
Localize,
Isolate
and
Correct
• Define Look at the symptom carefully and determine what circuits could be causing the
failure. Use your senses Sight, Smell, Touch and Hearing. Look for burned parts and check
for
p
ossible overheated com
p
onents. Ca
p
acitors will sometimes leak dielectric material and
ppp
give off a distinct odor. Frequency of power supplies will change with the load, or listen for
relay closing etc. Observation of the front Power LEDs may give some clues.
• Localize
A
fter carefull
y
checkin
g
the s
y
m
p
tom and determinin
g
the circuits to be checked
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and after giving a thorough examination using your senses the first check should always be
the DC Supply Voltages to those circuits under test. Always confirm the supplies are not only
the proper level but be sure they are noise free. If the supplies are missing check the
resistance for
p
ossible short circuits.
p
• Isolate To further isolate the failure, check for the proper waveforms with the
Oscilloscope to make a final determination of the failure. Look for correct Amplitude Phasing
and Timin
g
of the si
g
nals also check for the
p
ro
p
er Dut
y
C
y
cle of the si
g
nals. Sometimes
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“glitches” or “road bumps” will be an indication of an imminent failure.
• Correct
The final step is to correct the problem. Be careful of ESD and make sure to
check the DC Supplies for proper levels. Make all necessar
y
ad
j
ustments and lastl
y
alwa
y
s
June 2011 42PW350 Plasma
8
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perform a Safety AC Leakage Test before returning the product back to the Customer.