Standby Problem In Singer LCD TV Repaired
The complaint of this Singer LCD TV was in standby mode. You can see the standby LED in the below photo.
Standby problem usually due to few causes such as:
1) MCU IC got 5v/3.3v or 2.5 volt but cannot send out the “On” signal due to the ic itself have problem or the EEPROM/Flash rom IC have corrupted.
2) MCU IC could send out “On” signal but it can’t reach the main power supply section due to bad components in the optoisolator ic and surrounding components problem.
3) The DC supply input to the MCU/EEPROM IC may be improper due to power supply problem.
Obviously there are more causes but I guess these are the few common causes.
Even pressing the remote control and the TV front panel power button would not turn On the power.
Once the cover was removed I could clearly see two circuit boards. One is the power board and the other one is mainboard-see the photo below:
It was very clear to me that I could see bulged e-caps on the power supply board. There were five of them. All of them checked bad using my meter and the other one was tested good so I did not replace it.
It was a pretty straight forward job, just replace the bad e-caps, clean the circuit board and power On the set. See the result below:
Conclusion- Assuming if all the e-caps were good and output voltages were normal then I will troubleshoot the mainboard by checking on the DC supply input to the MCU IC. The DC supply usually are coming from the SMD voltage regulator ICs. These regulator ICs are prone to failure and could cause many weird symptoms. So if you are a beginner and wish to learn how to repair LCD TV then you can check on John’s ebook HERE on LCD TV repair.
This article was prepared for you by Suranga Bandara who owns an Electronics shop in Anuradapura, Sri Lanka.
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Note: You may check out his previous repair article in the below link: