Vizio E550i-b2 TV has no backlight, pic or sound. Replaced power and Main boards - still having the problem. Any suggestions? I have the TCON and LED Driver board left

This model set has local dimming and not a lot of issues with backlights failing, but it has issues with connector CN202 having bad solder joints from the factory. Chances are there isn't anything wrong with your old board other than bad solder joints and I have a feeling the replacement you got has the same issues but only a couple of them are bad making most the lamps light. If you've able to solder and have an iron you can repair it yourself, a little free advice is use a lot of flux to keep the connectors from wanting to solder together as they're quite close to each other.

First thing is test power supply voltages as the power board on this model has had some issues. You need to test the 12 Volt supply for correct voltage and ripple as cap failure is somewhat common. Don't worry about the 5 volt supply. If the voltage looks good you have a bad main board and that board will be hard to find and expensive, over $100 in most cases. As strange as it sounds a bad inferred sensor board will also make no sound but I can't say I've head of that issue being intermittent.

You need a new tv

Most likely you have a bad TCON board, one other thing to check is the connections going from the main board to the TCON and out to the panel, remove each one and replace it and see if that helps

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

If you can see an image with a flashlight and you can control the tv with the remote then the main board is not the problem. You've replaced the LED driver board, so that leaves the LED strips inside the LCD panel as the likely problem.

U are on the right track - problem is caused by the board that drives the backlighting - the inverter board.

If you can get the number for the board it may be available on the cheap on ebay.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electro-medical.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board

T'Con board fault. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
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