no power no standby light

I have a Vizio e470va I tried turning the tv on with the power button and on the remote and in both instances the outcome is the same. The tv does not power on and there is no illumination on the Vizio logo. I removed the back cover of the tv and tested the voltage on both 5v pins when the mainboard is connected. I am only reading 3.5 volts on both of the 5-volt pins. When I remove the mainboard from the equation and retest the 5-volt pins I get a constant 5 volts on both pins on the PSU. mainboard p/n TQACB 5K05606.


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Hi,

Please clarify your question.

You state "no power no standby light" and then say ".....the Vizio standby light on."

Which is it, on or off?

If on have you tried using both the TV power button and the remote control to try to turn it on, you didn't specify.

If not on, it's the mainboard that turns the standby power light on when it gets the standby voltage from the power board

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@jayeff sorry for the mistakes in the question. I tried turning the tv on with the power button and on the remote and in both instances the outcome is the same. The tv does not power on and there is no illumination on the Vizio logo. I removed the back cover of the tv and tested the voltage on both 5v pins when the mainboard is connected. I am only reading 3.5 volts on both of the 5-volt pins. When I remove the mainboard from the equation and retest the 5-volt pins I get a constant 5 volts on both pins on the PSU.

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Something most likely partly shorting the 5V rail to ground hence the lower reading. Try to follow the 5V rail on the main board to identify which components can be the culprit(s). IT could be a leaking capacitor or a damaged resistor (in my opinion)

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ok I managed to find the semantics of the mainboard also I did some more research on different troubleshooting paths to follow and one of the suggestions was to de-pin both 5-volt lines from the PSU and supply 5 volts from an external dc power supply. I got the test set up and applied my 5 volts to the required pins on the mainboard. I proceeded to turn the tv on the screen came to life I interacted with all of the functions on the tv and everything was working the only issue I noticed was the Vizio stand by light would not stay constant it was flickering on and off and there was a clicking sound coming from the tv's PSU. With the tv and the external power supply set to 5 volts, I got a reading of about 1 amp draw on my external PSU. I do not know if any of this information is helpful but I thought it wouldn't hurt to get it out there. Thank you for your replies and guidance thus far it is greatly appreciated any more incite you could offer would be awesome.

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Is anthing getting hot on your PSU?

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