Service Modes, Error Codes, and Fault Finding
EN 18
LGE PDP
5.
Figure 5-44 Screen display “Vertical lines”
One or Several Horizontal Lines on the Screen
1.
It may be caused by:
–
Open or short on SCAN FPC attached panel.
–
Defect on SCAN IC attached panel.
2.
Replace Y DRV board.
Figure 5-45 Screen display “Horizontal lines”
Low Brightness of Displayed Picture
1.
In this case, Z board operation is not correct.
2.
Check the power cord of Z board.
3.
Check the connector of Z board and CTRL board.
4.
Replace the CTRL board or Z board.
Partially Other Colour on Full White Screen or Partially
Discharge on Full Black Screen.
1.
Check the declination of Y board set-up and set-down
wave.
2.
Measure each output wave with oscilloscope (> 200 MHz)
and compare the data with below figure data. Adjust the Y
board Set_up (A) and Set_down (B) declination by
changing VR1 and VR2 as written on the adjustment label.
–
Measuring Point of Y board: B39
Figure 5-46 Y output voltage waveform
No Specified Brightness at Specified Colour
1.
Check the connector of CTRL board input signal.
2.
Replace the CTRL board.
5.2.3
Checking for Component Damage
Y IPM (IC 15) or Z IPM (IC 2)
When the internal Sustain_IGBT or ER_FET of Y IPM (IC15) or
Z IPM (IC2) is damaged, VS fuse is open and there will be no
picture.
•
Test Point: B32-GND (Y board), B28-GND (Z board).
•
Wave format: B32 (Y board) or B28 (Z board) has no output
wave.
•
Measure position: Sustain section, B32 wave of Y board
and B28 wave of Z board (full white pattern).
Figure 5-47 IPM normal output
Pass_Top FET (Y board: HS2)
When the Pass_Top FET is damaged, electric discharge of the
entire screen is generated.
•
Test Point: GND-B32 (Y board)
•
Wave format: When the Set_dn does not descend until -Vy.
Figure 5-48 Pass-Top FET defective
FET Assy (Y board: HS1)
When Set_Up FET is damaged, there will be no picture.
1.
Test Point: GND-B32 (Y board)
–
Wave format: Set_up waveform is not generated.
2.
When Set_Down FET is damaged, electric discharge of
entire screen is generated.
–
Test Point: GND-B32 (Y board)
–
Wave format: Set_down waveform is not generated.
–
Measure position: Reset wave of B32 (Y board) (full
white pattern)
It may show several vert.
lines in a quarter or other
division part of screen
including left case
F_15590_021.eps
040705
F_15590_022.eps
040705
It may show several horizontal
lines including left case
Vs
Vset_up (=Vs) = 187 ± 1V
- Vy = - 85 + 1V (Vr4)
B: Vset_down= 100 + 2 µs (Vr2)
A:10 + 2 µs
(Vr1)
F_15590_023.eps
040705
Y IPM
Z IPM
Y IPM
Z IPM
F_15590_024.eps
060605
pGGGGGT}
F_15590_025.eps
040705