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Old 03-25-2018, 01:39 PM   #102
Join Date: Apr 2013
City & State: Iowa
My Country: USA
I'm a: Hobbyist Tech
Posts: 33
Default Re: Vizio P502UI-B1E has no backlight, no voltage from driver board to LED's

Originally Posted by al1415 View Post
In the beginning on i had backlites when TV turned on, then when vizio logo go away just black screen. After plugging and unplugging and checking voltages i get only black screen and no backlites also no voltages going to T-Conn or LED driver board. On the main board their is A Synchronous Step-Down Converter location U712 Pin 2 was 1.3 volts now only .7 volts, also X201 has no voltage or the cap at connector for lvds cable to T-Conn no voltage where as before i lost backlites altogether i did have. I agree though issue is main board just what chip is the question. Could be U7612 breaking down under load maybe??
If U712 is a tps54328, pin 2 is the feedback. It should be at ~0.76V during normal operation according to the datasheet. I don't think that one is the issue. if the output voltage on that regulator is fine, I wouldn't worry about it.
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