I have a red flashing led on the power diaplay. I can turn the television on howere it will turn itself off with 2-3 munites of play time. I have tried power cycling the television and I have checked my powere sources.

The fan should run for a few minutes after shut off to cool the lamp down.

If I read and understand correctly somewhere in the cycle you are getting 5 red blinks? that is an error code........

Either you or I can Google the model number of the set with 5 blinks.....or visit the Sony site to see what it means.....

Power supply board is dead,replaced the power supply board will get power.

This is straight from the service manual (I'm not sure what the problem is but it sounds serious):

8.2. Power LED Flashing timing table
When an abnormality has occurred, the protection circuit operate and cuts the power supply. At this time, the defective line can be
identified by the number of flashes (red) of the power led indication at the front of the unit.
NUMBER OF FLASHES CIRCUIT MICRO PIN
1 LOAD SHORTAGE 92
2 OVER VOLAGE 93
3 FAN SOS 94
4 MAIN 3.3V 88
5 LAMP DISABLE 61
6 GC3FM-IIC IIC
7 GC3FS-IIC IIC
8 GC3I-IIC IIC
9 COLOR WHEEL STOP 110

remove back panel. blow out all the dust from all the components except the fan on the right.
Vacuum out all the dust.
Have you replaced the lamp? that would help too.
There are 2 small red lamp. One indicates HEAT problem. The other one is the LAMP indicator.

Needs new lamp or the fan is out.

The TV shutdown error code can help you with this problem. If the power led flashes green for 2 Min's then red. The Lamp led should flash red 1-2-3 or 4 time every 5 Min's. These are error codes that may point you in the right direction to you problem.

Replaced the sc board and tv works fine again.

3 red blinks means th lamp door in not on. if you have installed the lamp door corectly and it still does this solder all three pins together on the door switch.

capacitor problems in power supply or a regulater isolate the power suppley by disconecting the line output stage/unplug scan coils for example and run a 60w bulb as a dummy load one wire to earth and the other to rail voltage colecter of line output transister if the bulb glows steady the power supplys fine