LG El
e
c
t
r
on
ic
s
/DND QA
LG El
e
c
t
r
on
ic
s
/DND QA
LG El
e
c
t
r
on
ic
s
/DND QA
LG El
e
c
t
r
on
ic
s
/DND QA Gr
Gr
Gr
Gr
Name
No signal Vertical Bar
Symptom
Cause and Countermeasure
Realization
1.Cause : Bad IC2 (DA1)
8cm
When ASIC Chip(IC2 DA1 LGD4001) on Control Board gets
high temperature, you can observe it
(In normal temperature it’s O.K. )
▶
IC2 DA1(Data Arrange) No.162 Pin output is changing
depending on the temperature.
⇒
abnormal X-B’d Buffer IC
* Room temperature : 2.5V Output (Normal Pin = over 2.8V)
* Heated : 1.5V Output(Normal Pin = 2.7V )
⇒
⇒
⇒
⇒
Bad IC2 (DA1)
< Waveform of normal pin>
─
──
─
heated
< Waveform of abnormal pin >
─
──
─
heated
DA1
Buffer
DA1
Buffer
Buffer(74ACT541) waveform abnormally narrows.
→
→→
→
In this case, it is impossible for Flip Flop(74AC574) on
X B/D to read data.
2. Countermeasure : Replace IC2
