Daewoo DP-42GM, Service Manual

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Main PCB Trouble Diagnosis
10-3. Trouble Diagnosis and Repairing Method for Representative Symptoms
(1)When POWER SHUT DOWN occurs
<1> Definition of SHUT DOWN
- When LED Color is Green, can t hear POWER operating sound. (Red : STAND BY, Green :
Operating)
- When Turn OFF and turn ON AC SWITCH again, and turn Remote Control POWER ON ,
POWER RELAY do not operate normally, and POWER operating sound can not be detected.
<2> PCB Check Priority (Left to Right)
- POWER, X-SUS, Y-SUS, SCANL/H, DATA, DIGITAL, VIDEO, CONN-LEFT/RIGHT
<3> Trouble Repairing Procedure
- As shown in FIG<10-1>, first check which of LOW VOLTAGE part or HIGH VOLTAGE
part has a trouble.
- If LOW VOLTAGE part is broken is checked, as shown in FIG<10-2> diagnose the SET and
then replace the broken PCB.
- If HIGH VOLTAGE part is broken is checked, as shown in FIG<10-3>
diagnose the SET and then replace the broken PCB.
- <Note.1> When disconnecting/connecting connectors, you must turn OFF the AC power and
check the direction/position of them before working.
- <Note.2> If you turn the SET ON with X-SUS PCB and Y-SUS PCB s POWER
CONNECTORS (P101A, P201A) disconnected, although you turn the SET OFF
again, Remaining Voltage still exists in the POWER PCB. Therefore assemble the
connectors several minutes after. Or, check the Remaining Voltage (Vsus, Vadd) by
multimeter. If Vsus is less 10V, connect connectors. Connecting connectors with the
Remaining Voltage (Vsus,Vadd) over 10V could generate sparks and be dangerous to
Operators or SET.
(2)When Screen Discharge (luminescence) is abnormal
<1> Definition of Abnormal Screen Discharge (luminescence)
- In Entire or part of screen, irregular and unstable Discharge arises. (Refer to Trouble Symptom
Picture<8>)
- This symptoms are divided into No Discharge and Wrong Discharge
- No Discharge : Pixels which should discharge do not emit light. When WHITE PATTERN is
displayed, one of RED, GREEN, BLUE does not emit light, so CYAN(GREEN+BLUE),
MAGENTA(RED+BLUE) or YELLOW(RED+GREEN) shows on some part of the screen.
- Wrong Discharge : Pixels which should not discharge emit light. When single color like RED,
GREEN, BLUE pattern is displayed, CYAN(GREEN+BLUE), MAGENTA(RED+BLUE) or
YELLOW(RED+GREEN) shows on some part of the screen.
- If No Discharge or Wrong Discharge is severe, it can be easily detected when any moving
image is displayed. But if it is not severe, it can be detected only when certain particular