42ED41 - HITACHI PLASMA TV - VERTICAL LINE - TROUBLESHOOTING
UNDERSTANDING DEFECT TERMS:
The descriptions below all indicate the particular section which is
involved in the abnormality being displayed. Understand that if these lines
were only a single pixel in width, then the Panel itself is defective. If the
failure is being generated by a PWB and/or a connector, then the line will be
at least 8 pixels wide.
Address open (line off)
Vertical Influence from the Control,X-Drive Left and Right PWBs and COF.(Note:
Defect Line shown is on the front Right, so the X-Drive Left PWB would be
involved).
Note:
The Screen can be broken down into 7 Vertical Columns. Each of the
connectors from the Control, X-Drive Left and Right PWBs controls each
column. Try to determine which area of the
screen is affected to determine the PWB involved. Also, if the COF is
defective, the panel is defective and can not be repaired.
Address short (line on)
Vertical Influence from the Control,X-Drive Left and Right PWBs and COF.
(Note: Defect Line shown is on the front Right, so the X-Drive Left PWB
would be involved. The Screen can be
broken down into 7 Vertical Columns. Each of the connectors from the Control,
X-Drive Left and Right PWBs controls each column. Try to determine which area
of the screen is affected to determine the PWB involved. Also, if the COF is
defective, the panel is defective and can not be repaired.
The figure shows a back view of the Panel.
VERTICAL ADDRESS:
Vertical Addresses is controlled by the COF cables. COF stands for Chip
On Film. This means that the Ribbon Cable has embedded IC and resistors.
Note: There are 7 total COF cables controlling the Vertical Addresses.
They are broken down into 2, 3, 2. The 2 on the left are controlled by the
X-Drive Left PWB, the 3 in the middle are controlled by the Control (LVDS) PWB
and the 2 on the right are controlled by the X-Drive Right PWB. The Figure
below shows one of the COF cables. Note the chips, capacitors and resistors
mounted on the flexible ribbon cables. Also note there are 4 COF per cable. (4
X 7 = 24 COFs). 4 Per cable, 7 Cables.
COF (Chip On Film Cable):
Supplies a waveform which was generated from the Control PWB to the
panel and selects a output pin that is controlled by COF (Chip On Film) when it
will be on or off. 96 output pin per COF IC.
The higher the resolution, the less spare space where an IC can be
placed on the PWB without using IC PACKAGE, so a BARE IC is used embedded right
on the cable.
Because IC is not soldered on
PWB directly, soldering defect rate is decreased. COF failure requires Panel
replacement.
HORIZONTAL ADDRESS:
Horizontal Address is controlled by 6 Printed Circuit Cables. Supplies a driving waveform to PANEL by
connecting a PAD electrode of PANEL with PCB
(Y Drive and Z SUS).
There are two types of this for Y Drive PWB. One is single-sided,
another is double-side. These have a pattern on it .
For Z SUS PWB, there is no pattern , single-sided and Beta type (all of
copper surface).
For connecting a Logic signal between PWBs. The one shown here is P101
from the Control PWB to the Y SUS PWB.
There is 0.5mm pitch, 50 pin type and; 1mm pitch , 30 pin type.
