Trouble Shooting; Facts You Must Know When Diagnosing And Repairing; Representative Symptoms When Each Pcb Breaks Down - Daewoo DP-42SM Service Manual

9. TROUBLE SHOOTING

[NOTE] See II. PARTS of MODULE of this service manual for trouble shooting concerned to
MODULE with exception of VIDEO, JACK and POWER parts.
9-1. Facts you must know at trouble diagnosis or repairing
(1) The trouble diagnosis and repairing of set means Module Exchange . In other words, find out
which PCB modules are not working and replace them with normal PCB modules. Do not need to
fix broken PCB modules in themselves.
(2) This TROUBLE SHOOTING list only contains representative and simple PCB trouble diagnosis
and Module Exchange method. Therefore, if you find Sets that are difficult to diagnose or to
repair, contact Daewoo Electronics.
(3) Basic TROUBLE SHOOTING procedure Check Trouble Symptoms
Trouble Diagnosis
replacing Z-SUS, Y-SUS, POWER, VIDEO PCB, need Adjusting Procedure. Refer to I. 6.
Adjusting Method and II. 3. Adjustments)
PATTERN FULL WHITE), FUNCTION CHECK
(4) Keep broken PCB modules separately for replacing with new PCB modules.
(5) Required equipments for trouble diagnosis
- DIGITAL MULTIMETER (User Mode : measure DC VOLTAGE, measure DIODE VOLTAGE,
SHORT-OPEN TEST )
- Screwdriver (or electric screwdriver), plastic adjusting tool
(6) Each BLOCK operation was explained including DIGITAL OSCILLOSCOPE signal, but this is
reference only and applying them for repair is not necessary. (After additional education, DIGITAL
OSCILLOSCOPE could be used)
(7) Before assemble/disassemble PCBs, check to see if AC Switch is OFF .
(8) After replacing Z-SUS, Y-SUS, POWER, VIDEO PCB, the PCB needs extra adjustment. (Refer to
I. 6. Adjusting Method and II. 3. Adjustments)
(9) After the set is repaired, leave BACK COVER open for followings. Do HEATRUN for at least 30
minutes by inputting TEST PATTERN of SERVICE MODE (Refer to Service Manual I.5. Service
Mode) FULL WHITE. Check the screen conditions and basic functions (remote control operation
etc.).
(10) After BACK COVER is closed, redo HEATRUN for at least one hour by inputting FULL
WHITE using TEST PATTERN of SERVICE MODE. Check the screen conditions and basic
functions.

9-2. Representative Symptoms When Each PCB Breaks Down.

(1) Symptoms of POWER PCB Trouble
<Symptom.1> Not even weak discharge (luminescence) shows on screen.
<Symptom.2> Discharge (luminescence) on screen is unstable
<Symptom.3> Set is producing unusual noise
<Symptom.4> POWER SHUT DOWN occur (refer to Service Manual I. 9-3)
(2) Symptoms of VIDEO or JACK PCB Trouble
<Symptom.1> Only weak discharge (luminescence) shows on screen, but No Data is on screen
<Symptom.2> Screen DATA is abnormal
<Symptom.3> Particular input signal (Video, PC or Component etc.) does not operate
Replace broken PCB module Adjust new PCB module (when
HEATRUN (for at least 30 minutes, input TEST
Repair Complete.
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Detach BACK COVER