Daewoo DP-42GM, Service Manual

Page: 74 / 124

-74-
TROUBLE SHOOTING
(Note.1) SCAN PCB is divided into SCANH PCB (drive upper screen) and SCANL PCB (drive
lower screen). Each SCAN PCB contains four (64 PIN Output) SCAN DRIVER IC.
SCANH PCB drives upper 240 lines out of 480 total lines and SCANL PCB drives
lower 240 lines. Therefore, if either screen s upper or lower part is abnormal, then it
is possible that one of SCANH PCB or SCANL PCB is broken or having a bad
CONNECTION.
(Note.2) When SCAN PCB has some problems, those are most likely bad CONNECTOR
CONNECTION caused by dust or extraneous material. Therefore, check the condition
of CONNCETOR CONNECTION before diagnoses the PCB.
<Symptom.1> Horizontal lines (BLACK or irregular data, group or single) occur. (refer to
Trouble Symptom Picture <5> ~ <12> )
<Symptom.2> Upper and lower screen overlap each other. ( Upper data influence lower data,
refer to Trouble Symptom Picture <8> )
<Symptom.3> Not even weak discharge (luminescence) shows on screen.
<Symptom.4> Discharge (luminescence) on screen is unstable (refer to Trouble
Symptom Picture <8> )
<Symptom.5> POWER SHUT DOWN occur ( refer to Service Manual 10-3 )
(3)Symptoms of DATA COF Trouble
(Note.1) DATA COF consists of total 7 PADs in a SET. Each COF PAD consists of total four
96 PIN output DATA DRIVER IC , which drives one-seventh part in total
2559(=853*3(R,G,B)) vertical lines. Therefore, if specific screen part is abnormal it is
likely that particular DATA COF is broken or BAD CONNECTION. Moreover,
DATA COF is connected to DATA Electrode (Z Electrode : Vertical Direction) of
PANEL by HEAT COMPRESSION Processing. So, if DATA COF has a trouble, the
entire PANEL must be replaced.
(Note.2) DATA COF s Trouble is more likely caused by BAD CONNECTOR CONNECTION
due to dust or extraneous material. Therefore, make sure to check the related
CONNECTOR CONNECTION.
<Symptom.1> Vertical line (BLACK or abnormal data, group or single) occur ( refer to Trouble
Symptom Picture <1> ~ <4> )
<Symptom.2> For particular vertical BLOCK, Discharge (luminescence) is unstable or not
operating. ( refer to Trouble Symptom Picture <2>, <4> )
<Symptom.3> POWER SHUT DOWN occur ( refer to Service Manual 10-3 )
(4)Symptoms of POWER PCB Trouble
<Symptom.1> Not even weak discharge (luminescence) shows on screen.
<Symptom.2> Discharge (luminescence) on screen is unstable (refer to Trouble
Symptom Picture<8> )
<Symptom.3> Set is producing unusual noise