Well over a year ago, my Uncle gave me an older 26" 720p LCD HDTV. Clearly, it is one of the first-generation flat-panel screens, as it has some quirks. The color isn't very consistent, and it temporarily burns in static images. Other than that, it's been a great TV, and we've gotten a lot of use out of it. We were very dismayed when we discovered that the sound was cutting out after 15-30 minutes of use, and we really didn't want to spend $200+ on a new TV. I quickly traced the problem to heat, as the problem only appeared at the beginning of the summer, and the sound seemed to last longer with a small fan propped up behind the TV. See how I revived our HDTV after the break!
The first thing I did was pop the plastic back off the TV to see how it is cooled. The biggest problem was the RF shield, there were virtually no cooling holes, making the louvers on the plastic back totally useless. A single rubber-mounted 2" fan blew a tiny bit of air across the power supply, but it didn't touch any of the chips on the controller board.
I pulled off the RF shield and set up a small fan blowing across the chips (which got very hot to the touch on their own). The problem was solved immediately.
I pulled the back cover off, and decided where to put my fans. A 2" fan covers a group of video processing chips towards the middle, and a 1" fan focuses on a chip next to the speaker wires on the left. The fans were free; I won them in a raffle for a "box of junk" from The Reuseum. Just what I needed! I went a bit on the small side with the holes.
The plastic on this TV is ABS. I used a small cutting tool on a Dremel for the big stuff, and finished it out with a drum sander attachment. The cutting tool didn't cut it as much as it just melted it, but the drum sander allowed me to get good, even circles. The hole for the smaller 1" fan on the left was a bit tougher because of the louvers. It doesn't look quite as good. If there is a better way to cut ABS plastic, I'd like to hear about it.
Bolted in the fan with some 1 1/2" #6 bolts that were left over from my Printrbot project.
I tapped into the power for the existing fan. Hopefully I won't overload that circuit, but I don't think it will be a problem. Strip, twist, crimp, solder, heatshrink, repeat.
Finished! So far, the audio has worked continuously for about one hour straight. If the two fans don't solve the problem, I'll take it to the next level by applying adhesive heat sinks, like you see being used on the Raspberry Pi. The project took me a total of about $45 minutes, and didn't cost me anything, because I had everything I needed on hand. The 2" fan is a bit noisy, but not so much so that it causes a problem. If it starts to bug me, I can swap it out for another easily. Below the 2" fan, I put a nice scrape in the plastic with a slip of the dremel. Some Acetone on a rag with some wiping and dabbing roughened the texture on the spot, hiding the scrape reasonably well.
Now I won't have to shell out over $200 for a new TV! Awesome!