Standby Problem In LCD TV

I always enjoy reading your repair post’s I am in lcd tv repair as a hobby but I have learned
a lot from reading your post and also I have purchased some of your ebooks I find my self going back time after time reading the switch mode power supply book it it’s a great book. I am also a member of the LCD tv repair site another great place to learn.
But I have a SOYO MT-SYTPT2627AB-7G271 that I have not been able to find any info. on
wondering you may have ran across one of these lcd tv’s. tv is dead I do have a 5volts at one of the outputs but no standby volts (3.3) output or 12volts output or 24volts output
but I am still trouble shooting it and I will not give up…lol

Answer:

Thanks for the support on my ebooks. In your case it could be the problem of bad MCU ic. I’m afraid the programs could have been corrupted. Before that make sure the 5volt is really stable. Another suspect would be the power supply optoisolator circuit. This means if the MCU sends out an “On” signal and this signal did not reach the opto ic (or the opto IC circuit have problem) then the main power supply will not be able to work. With the help of a schematic then it will be easier to locate if the MCU IC indeed got send out the “On signal”.

In certain designs, a relay and a driver transistor is used where the “On signal” will trigger the driver transistor causing the Relay to conduct and this will cause the AC main supply to be applied to the main power supply thus producing all the DC output voltages at the secondary side.

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2 Comments

1. 

   Raymundo Saura

   January 21, 2014 at 10:30 am

   thanks sir justine i learning a lot from you thanks and GOD bless

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   • 

     Jestine Yong

     January 21, 2014 at 11:14 am

     HI Raymundo,

     You are welcome.

     Jestine

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