Originally Posted by davidke
[BEGIN wild theory mode]
Instead of heating the entire unit, have any you considered just placing the heated tip of a screwdriver on the service mode sensor just like the samsung teks use to unbrick all the phones we are sending back? It just needs to be warm. Some sensors are so sensitive that they dont need to be heated at all, just press the 3 keys and you are good to go. This is the sensor that they are going to disable in an upcomming fix that they are releasing because of community pressure.
[can't post links]
[END wild theory mode] ;)
Nice theory, but my guess would be that this hole stems from the molding process of the body
On a more serious note, in a different thread someone mentioned that it could be a timing issue. This is actually realistic.
In laymen terms:
Digital Signals don't change their level instantanious. If you want to change a 1 into a 0, you need to get all the electrons which produce the "1-voltage" to go somewhere else to have your "0-voltage". This takes time, not much but enough to be a major design factor in digital electronics. If you have two chips communicating, you don't want the first on to look what the second sends, before the signal levels have stabilized. The 3 button issue could very well be such an issue with some timing beeing off far enough to have the the 3-button combo never register with the CPU.
How can heat change this?
Well, simplified its like this: Good conductors (e.g. metals) have a lot of electrons who are not that closely bonded with the atoms. This means they can roam freely and carry electrical current (which is nothing else, then electrons moving around). Isolators are materials which have all their electrons fused to the atoms and therefore don't permit free electron flow. Semiconductors are materials which lay somewhere in the middle. Their electrons stick to the atoms too but the get knocked off easly by things like radiation in the form of heat, light, radioactivity and so on. This in itself is not the primary mechanism which gives silicon chips their electrical properties, we actually want them to have. That is achieved by diluting the pure silicon chrystal with certain elements but thats not the point here. Whats important is, that temperature is a factor in the conductivity of a semiconductor. Temperature can change the behavior of chips, espeacily the timing behavior. The reason for this is, that higher temperature means more free electrons which means more conductivety which means faster moving electrons, which means faster changeing signal levels. Theoretcally it is possible, that by this mechanism and pure chance, the 3-button combo works in a heated SGS. It would be interesting to heat up only certain chips on the board and see which one is responsible. Not that I'm going to try that with my (until know) unbricked phone
If anyone of you wonders why you cool your CPU, when it should get faster when more hot: Remember, that a CPU is a block of silicon which has very specific conduction paths embeded into it to make it function as a CPU. Heating it up will lower resitance in the whole chip, making it eventually a whole big conductive lump of silicon. In that case, current will simply flow from the + to the - terminal, bypass all the logic gates and roast you chip
So leave the cooler on kids.