I have recently been repairing iphones and while doing this I have notice something in their construction that I thought we should have. Both the iphone 3 and 4 have a mylar mirror coating on the rear of the LCD to reflect heat away from the lcd and touchscreen, and it really works well. If you have an Iphone check it out, even when the cpu is flying the back gets hot but the screen stays cool. This got me thinking about the vega and how hot it gets running roms like VegaICS and Vegacomb. This can make touchscreens wig out and is uncomfortable. The design is flawed. There is a Mylar sheet in the vega but its completly in the wrong place. It is in the right place to be an RF sheild (thats probably what its for) but for cooling its about as much use as a 3 bar fire. When I am using my vega (playing games) it gets so hot inside that I can feel the heat flowing out of the hole for the dock connector. If I lay back, with the bottom of the vega resting on my stomach and I have a tee shirt on it gets hot enough to become uncomfortable so I have to move it. The Mylar sheet stuck to the back of the vega is reflecting heat back at the motherboard LCD and touchscreen like a little oven. The only place for the heat to escape is through the LCD, touchscreen and the other small gaps and holes around the vega. The metal panel bettween the LCD and motherboard will slow down the heating of the touchscreen but not much and will probably just be trapping heat when it gets up to temperature.
So to cool down the vega.
This is really simple. I ordered a small sheet of dimple mylar off eBay (non-conductive and disapates heat better than normal mylar preventing heat spots. apparently:). I have put it under the motherboard and on the back of the LCD. I also removed the mylar from the back of the rear panel. For good measure I cut a pieces of aluminum off a PC heat sink and fixed them to the Tegra chip and the ram chips (with alaska sheet type heat sink stuff, that's a technical term;) ). The heat sinks are probably overkill but it cant hurt and may meen overclocking will be cooler and therfore more stable.
I tested it with and without the heat sinks and the overall temperature is significantly cooler on both. The screen now stays cool all the time, even when charging and using the cpu hard. The back still gets warm but no where near as hot as before. With the Addition of the heat sinks didn't noticably reduce the temperature but they will come into play when ICS gets overclocked.
A nice side effect is the charger no longer causes the touchscreen to freak out (altough this could be eduardo's new driver). Fine accuracy is reduced while plugged in but the screen no longer double/phantom clicks and is usable for everything but drawing.
Overall I am really happy with the mod. It's cheap and easy to do and cools the vega a lot. Next time I have the back off I may add another peice near the charge jack to try to completly remove the charge/accuracy problem. I have not noticed any problems with interferance caused by removing the mylar off the inside of the back panel although my neibours telly could be going haywire without me knowing (not my problem).
Heres some pictures of what I did.
The back of the LCD covered with mylar (hard to get a good picure because of the reflection.
The metal panel back in with more mylar where the battery and motherboard are mounted, holes cut in mylar for the motherboard mounting screws.
Everything back in except the battery.
This show the original mylar sheet and where it was inside the back panel. Now removed and binned.
Running as cool as a cucumber
Edited by richardmlea, 06 April 2012 - 06:10 PM.