Why won't my tv stay on/off?

You need to disconnect the power from this tv, then press and hold the power button down for 15 seconds to drain the charge off the circuit boards inside. Then plug it back in and start over. If this does not solve the problem you may need to have it checked out by a repairman. You should still be under warranty so report the problem and file a warranty claim.

Easiest TV repair How to Fix Power TV turns off freezes or won turn on watch this video not sure it will help you but it might tell you why yours is not working.

when lcd tv`s fail to power up, but stay on standby. It is usually because of bad capacitors on the power board. My 22" lcd monitor did the same. It would not come off of standby. It starts with them being slow to turn on. "Sound familiar"? I fixed mine by changing the bad caps. There were two of them.

Here's is what you need to look for when describing a problem for troubleshooting purposes:

0) What model is the TV (you've covered that)

1) Does the TV respond to command to turn on?
(yes - continue; no - 70% bad power, 30% bad main board)

2) Once it responds (clicks), does a front LED or other indication show that it turns on? It's OK if there's no display.

(that can be model specific and is not certain indication for anything until known what is specific for the model)

3) If such an indication comes up does it remain on until you act or does it go off by itself?
(Stays on - power supply likely good; turns off - power supply *may* be good, but not certain)

4) If the power indication stays on by itself can you make it go off by pressing the power button or do you have to disconnect from AC power?
(responds to power off - 90% power supply likely OK and 90% OK main board; does not respond to power off - 90% bad main board)

Here is a link for test/repair of the power supply of your TV, hope it would help:

http://www.coppelltvrepair.com/p/895/samsung-pn58a550s1fxza-power-supply-repair-service-for-dead-or-clicking-on-and-off-problem

It could but it could be about 50 other things as well. You have a voltmeter, and know how to use it? going to need a service manual as well.

Quite possibly one of the heat sinks has come loose or a power supply cooling fan has failed.
Have you tried blowing it out using canned air?

checked the fuse the set has connected to where the power cord goes?

hi; you need to replace the lamp of your projection tv.
these could help you.

Bad capacitors on power supply board they will be vented or swollen on Top. 1000uf 2200uf 10v 3300uf 10v

You have a power supply problem. Within about 32 seconds the picture drops out because the backlite transformers shutdown. Yoy will have to find a new power supply or have some one fix yours.