MarkT:
An external regulator on a heatsink is the way to go. Certainly take the LED's off the 5V pin, the ethernet shield presumably plugs into the 5V pin anyway and you'll have to live with that (about 150ma??)That switchmode power supply should be giving out 5.0V +/-0.1V if it was any good at all - looks like its cheap dangerous junk: bin it. You may have damaged the Mega (6V is the abs max for the ATmega microcontrollers).
Give the seller negative feedback if that supply really is giving out 6.6V...
Thanks Mark, unfortunately i already voted time ago for the item.
The Mega is alive as if I plug it through the USB port it starts up and starts working, however the built in regulator starts to heat up, and voltage starts dropping till it gets to around 4,2 and lcd dimms and arduino stops working.
might it be that i have fried just the regulator? is it possible to replace it for a 7805 just soldering it on top? (removing the old one)
the led is only 20mA, but i really dont understand why all this is happening i have seen plenty of projects running from the arduino power without so much trouble. and even I have a very similar components proyect running from the arduino regulator.
any further help is much appreciated.
(at the moment the regulator is reading:
Vin = 7.6 V
Vout = 1.6 V
so i guess it is damaged? as i said, replaceble with a 7805?