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Vizio sv420xvt when turned on no blue screen,millions of red and yellow dots.Need to know what board to change and hope it is not the lcd panel

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You cannot know what board is involved without testing the TV. Testing requires skills and training.

The faulty board is likely the digital controller board(Vizio 3642-0492-0150), which is the main board inside the TV.

Before replacing the main board, the Power Supply and the must be tested.

On this 42'' there is also a Daughter Bd Assy, and T-Con Board that must also be tested.

Testing is done at component level, mainly reading volts in strategic points and checking components for continuity.

Here a general procedure explaining how to test the power board. Disregard the part on inverter as this is unlikely responsible for the symptoms you have described:How to test an LCD TV or monitor PSU

Regarding inputs, this can also be responsible, and may be tested by simply using the TV on different connections. Here the boards :HDMI Input, and AV INPUT .

Before doing anything else call Vizio at the number listed on the owners manual, to verify warranty status and to check the factory quote on repair.



Posted on May 06, 2010


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if the line was all the way it would likely have been the LCD itself, which is not repairable; chances are still that's what it is, of course, but I can't remember seeing an LCD problem as you describe it.

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No signal

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I’m happy to assist further over the phone at

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