samsung tv screen goes blank by itself - help?

I have had the back off and dusted it with compressed air. There was very little dust anywhere. The fan is also operating properly. In addition to problem mentioned above (picture going black while lamp remains on, which is happening several times each evening), now the dvd audio is raspy. Satellite audio is perfect. I have tried new cables, switching from component (rgb) cables to RCA, connecting dvd player to other inputs including the one the satellite usually is connected to, dvd player works perfectly connected to a different tv. I have tried troubleshooting every possibility. Someone suggested the capacitors may be failing. If this is the problem, does anyone have any idea how much it may cost to replace the capacitors? I can buy a new tv for $700-800 (same size and brand), so I don't want to be nickel-and-dimed to death with this one. If it were a heat buildup issue, you would think the tv would need to cool for a bit before it would come back on; however, it turns on as soon as I restart it after the picture goes black. ??

The current bad caps plague symptom is issues at cold temps or when it's first turned on. Your set symptoms point me to heat issues. If the cleaning didn't help the usual tech will swap boards. Be sure to do your user serviceable items like check for firmware updates first.

Then about the other old age issue. Heatsink compound can dry and cease to do its work. Your older tv shop will pull the heatsinks if there is any sign of this issue and apply fresh compound. DEFINITELY not user serviceable. Even techs just swap boards.
Bob

Is the firmware update something I can do? If I thought I could have the tv repaired for a couple of hundred dollars, I would consider it. Diagnosis alone is $50. Then if the heat sink was serviced and the board replaced on top of that, would it be smarter to replace the tv since this may be the beginning of other issues? I will try to update the firmware first and see if that resolves the problem. Stay tuned Thanks for your help. I'll let you know how it goes.

It appears to be work that is considered user serviceable.

As to the other questions, I need new batteries for my crystal ball but those are on back order.
Bob

PS. In other words I can't tell the future.

According to Samsung, there are no firmware updates for this tv. I will take your advice and look into replacing the board. Thanks for your help!!