Replacing the tuner in your LCD TV can become necessary if it has gone bad. Fortunately, LCD TVs are made in layers to facilitate manufacturing. There is the LCD itself upon which the circuit board is stacked, and there is the tuner board behind it. This allows companies to sell the same TV in different countries by just replacing the tuner board, instead of having to build a whole new LCD TV for each country.
Turn the TV off. Put on an antistatic bracelet so that your static electricity does not shock the TV's circuit and possibly cause damage. Turn the TV around 180 degrees so that the rear is now facing you. Pull the power plug out of the back of the TV, even though it is off, there is still a residual charge going through to keep its memory circuits alive.
Locate the screws that anchor the rear of the LCD TV. The bigger the TV, the more screws there will be. Unscrew the screws with a hand screwdriver, do not use any power tool, as it may damage the TV with its excessive torque. Keep track of the screws -- obtaining replacements can be difficult.
Pull the back casing off and place it to the side where it will not be damaged. The plastic is not meant to take any weight, so an errant misstep could crack it. Look inside the TV and locate the circuit board nearest to you, this will be the tuner board. It is anchored with four screws to plastic pylons that piece the circuit underneath. Unscrew these screws and keep them separate from the exterior screws, since they are of a different length.
Pull the tuner board off the pylons by hand, but not completely as there will be wires underneath the board. Detach the wires by hand. They just plug into corresponding ports. Now pull the tuner board all the way out. Put the replacement board in by first connecting the wires to the tuner board. The exact placement will depend on your model of LCD TV. Screw the tuner board onto the plastic pylons with the correct interior screws.
Place the back casing back onto the LCD TV and re-screw the exterior screws back in. Plug the power back in, turn the TV around and turn it on.