HOW TO REPLACE INFRARED SENSOR IN A TV

Infrared sensor is a component which receives the infrared rays emitted by the remote control handset, and amplify them to digital signals, which in turn processed by main system control IC.  As we push different buttons on the remote control handset, infrared rays of different frequencies are emitted from the infrared emitting diode, fitted at the front side of remote control.  Frequency of emitting signals for each press of remote buttons will be unique to each other.  Infrared rays thus emitted from the remote control will pass through a small window at the front panel of every TVs, which in turn fall at the infrared sensor fitted just behind this infrared sensor window of the   There are so may types of infrared sensors, used by several brands.  A typical one will look somewhat brownish black in color, and will have three solder terminals. See some types.

Here you can see many types, but all of them have only three solder terminals.  This component is nothing but a photo transistor and an associated pre-amplifier section to amplify the signal falling on to the base of the photo transistor.  As you know, the infrared rays are invisible to human eye.  But it can be sensed bu the photo transistor inside the infrared sensor. 

The sensed signals will then passed to main system control IC for process. If the infrared sensor have some internal fault, these signals cannot be send to main system control IC, and the TV set won't respond to remote control, even-though the remote control is perfect in all respect. See some equivalent schematics and see how the infrared sensor is connected to.

Just see, out of three solder terminals, one terminal [3] will be soldered to ground, an other one [2] is connected to an outside transistor via a resistor, and the third one is connected to +ve power supply via a current limiting resistor. In  some sets, these sensors will be connected directly to certain pins of the main system control IC directly, as shown above.
How to replace them is our question here.  It is very easy for anyone who have knowledge in electronics.  Just locate this device behind the infrared sensor window at the front panel of the TV.  you have to open the TV, and unscrew out the circuit board fitted behind the front panel of the TV.  In some sets, it will be connected to main circuit board itself, and when we push in the main circuit board into the set, the infrared sensor will come just behind the infrared window at the front panel of the TV. The design will be thus. 
To replace it, you have to unsolder the three terminals, and take it out.  It will have a number printed on it [usually can be seen at its side].  When buying a new one, insist on same number, because some type will have special characteristics.
This component is very easy to get from most of the electronic spare part selling shops at your town, and won't cost more. Replace it with same mounting as the damaged one was.  There will be one terminal apart from the other two.  You can detect it very easily, and can locate the position.