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OK first, after spending three nights reading thread after thread trying to find a solution to my problem, I quickly came to the conclusion that although there are a lot of posts about issues, there are very few fixes noted.

So, let me describe my symptoms first.. very similar to many others my HLP4663 was working fine one day and all of a sudden it shut itself off. Within a few seconds it turned itself back on. It repeated this several more times until after maybe the fourth time and then the dreaded three lamps started blinking on the front.

Now to be more specific the picture would drop out first and then the sound would cut out a few seconds later. Each time it tried to turn back on the lamp would light for a few seconds and shut back down. Unplugging the set got it to reset once or twice and it would trun on and function for another 20 minutes or so until it started shutting down again. Finally after doing this a few more times she just stopped working.

So to these threads I came reading all I could. I considered all things; balast, bulb, pwr spply, color wheel, dmd brd,etc....
All these parts are not particularly cheap and throwing in the above parts would end up running $700+ I even purchased a Service Manual and read it all the way through. My attention was directed to the thermostat. The reason being, it seemed to me the TV was turning itself off for some reason and perhaps it was thinking it was overheating.

My fix.....I did a serch for a thermostat #BP91-00612A and found one for under $3 with $7 s&h. Received it yesterday, swapped it out and I'm happy to report, the TV is working like a champ again.

So, sorry for the lengthy post, but I wanted to explain my symptoms as well as what I was considering replacing and finally what I decided to try and most importantly what the fix ended up being. I checked in the service manual how to the test for the thermostat.
1) find the Actuator Board, it is the small PC board approx 4" X 4" that the rear door switch is plugged into- so is the thermostat.
2) find the plug that the thermostat plugs into on this board (connector CN106) and remove the wire.
3) place a jumper accross this plug and try the TV. (remember to get to this board you'll have to take the back panel and light door off - so, you'll have to tape the door switch closed)
4) if the TV works simply swap out the thermostat.

I realize this may not be everyone's problem, but it is definitely the cheapest place to start.

Very interesting. Do you maybe have pics showing how you placed the jumper?

great post, i tryed the same thing on sunday seemed logical to me, fans work ect bulb lights up to full brightness and shuts down. bulb looks good (not burned) i have taken all the boards out blew off dust with air, vacuum. i tried jumping the thermo switch with a staple in the plug. maybe this was not enough. I will try with better wire to be sure. I like the fact that you completed your thread in stead of the one liners i have been reading also since saturday whan this all started. if you read my piece of thread i was trying to be detailed too. i have photos of evrything and a pretty good on of the thermo switch. I work on computers and find this no differint. I was looking for a service manual tonight where did you get yours? as my tv is still not working. i was going to replace the ballist next but i will try jumping out the thermo switch again. thank you

mainesheets, be sure that when you have the back cover and lamp door off the TV and you try to jump the thermostat you don't forget to "close" the lamp door switch with a piece of tape to hold it in the closed position.

I read your other post and I've also seen others say you need to reset the lamp timer in the service menu. I'm certainly not an expert on these things but I find it very hard to believe the lamp timer has anything to do with the actual performance of the TV. It seems to me to just be used as a gauge to the lamp life. I bought my TV refurbished from Sears. They said it had a new lamp installed. A year and a half later it blew and I replaced the lamp. When I did I went into the service menu to reset the lamp timer and it had 16,000+ hours on it. The TV was working fine up until the lamp blew. I reset the timer but I serioulsy doubt it has anything to do with the TV working or not.

Nothing in the service manual or the owner's manual (for that matter) speaks to this.

I got the service manual from here: http://www.service-docs.com/store/index.html for 12.99

I got the thermostat from here: http://www.partstore.com/Part/Samsung/S ... A/New.aspx for $10 w/ shipping

Here's a link to a vid (1 of 5 actually) to show the steps you have to go through to get to the screws on the thermostat. This guy was replacing his color wheel, but most of the same steps need to be followed to be able to slide the light engine assembly out from the TV chassis. You need to do this because the screws for the thermostat can not be reached while it's in the cabinet. Good luck..

UPDATE: just wanted to let folks know it's been almost two months now and TV is still working fine. If you're having similar symptoms, consider this VERY inexpensive fix !

Just bumping... to let all know that this February will be 6 mos since replacing the thermostat and all is still well with the TV. Hopefully this may help someone else with similar issues.