Samsung PL-42Q91HDP Service Manual page 30

When the unit is repeatedly turned on and off
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Symptom - The SMPS relay is repeatedly turned on and off.
In general, the SMPS relay repeatedly turns on and off by the protection function due to a defect on a board
connected to the SMPS.
- Disconnect all cables from the SMPS, operate the SMPS alone and check if the SMPS works properly and if
Major Checklist each voltage output is correct.
- If the symptom continues even when SMPS is operated alone, replace the SMPS.
- If the symptom is not observed when operating the SMPS alone, find any defective assemblies by connecting
the cables one by one.
Troubleshooting
Procedures
When separating and connecting the cables such as CN810, CN809, CN808, CN807 of the Main SMPS, CN4701
Caution of the X Main Board, and CN5707 of the Y Main Board, a spark may be generated by the electric charge of the
high capacity capacitor. Therefore, wait some time after disconnecting the power cord from the unit.
Samsung Electronics
Does the symptom continue when
connecting the power after removing
①
CN810 from the SMPS?
Yes
Does the symptom continue when
②
connecting the power after removing
CN809 from the SMPS?
Yes
Does the symptom continue when
③
connecting the power after removing
CN807 from the SMPS?
Yes
Replace the SMPS
No
Replace the Y Main Board
No
Replace the X Main Board
No
Replace the Logic Board
Troubleshooting
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