I know it is too late, but I will try to explain in a way that everyone can understand.
1: do you have a multimeter?
if you do that's great, if you don't, go buy one, you need it for lots of hacking activities...
2: The basic usage of the multimeter is to check resistance. if the resistance is close to 0, which mean it is connected or in another word, short circuit. If the resistance is infinite, which means open circuit, or in another word, if you don't connect your multimeter's red/black probe to anything, the resistance will read infinite, so it is open circuit.
3: why you smell smoke or the traces are burnt? you have to know the Ohm's law.
so what's Ohm's law? it states the current flow through a conductor is determined by the voltage on the conductor and the resistance. The mathematical way to express this is:
I = U/R
I: the current through the conductor
U: the voltage on the conductor
R: the resistance of the conductor
From this mathematical experssion, you can read that the lower resistance, the higher current.
You see the smoke or burnt because the 'conductor' cannot bear the power on it, in electronic work, there is a mathematical formula to calculate the power:
The power law equation:
P = U*I
P: power in watt
U: voltage in volt
I: current, in amp.
you know the Ohm's law now, let's do some calculation:
I = U/R
so
P=U*I = U * (U/R) = (U*U)/R
The lower resistance the higher power.
Now let's apply this theory to our scenario.
On most PCB, the mesh is connected to GND. so when you rejoin the 3.3v trace, you made a tiny 'bridge' between the 3.3v trace and the mesh (GND), you effectively create a tiny 'conductor', who's resistance is very very low, for example, 0.1, 0.01 or even 0.001 Ohm. Now the thing is, one end of the 'conductor' is connected to 3.3v trace, and the other end connect the GND, which means the voltage on this 'conductor' is 3.3v.
So let do some calculation:
Assume the resistance of the 'conductor' is 0.1ohm, the power on it is:
P=(U*U)/R = (3.3*3.3)/0.1 = 108 Watt
if the conductor's resistance is 0.01 ohm, the power on it is: (3.3*3.3)/0.01 = 1080 Watt
My desktop light is 60W, my TV is rated 200W... so you have a scene now how big it is for this tiny 'conductor'... since the power is so high it cannot bear the energy applied on it, so it burns (or start fire), fortunately enough, when it burns, the tiny bridge between 3.3v and GND is damaged, it no longer connects the 3.3V with the GND... so the resistance increases from 0.1 or 0.001 to an infinite number, and it's open circuit again....
Now, if you have a multimeter, you should know what to do now...
Make sure the silver glue does NOT touch anything else other than the trace you are fixing! Use the multimete to check the resistance between the trace you are fixing and the traces/mesh surround it, they should NOT read 0!
Let me know if this makes sense.
When I applied the silver stuff to the PCB from the Lite-On solderless guide and waited for it to dry, I turned it on and it worked for a split second, then I smelled smoked and watched this glowing light coming from the PCB.
I guess the glue must have touched a grounded contact.
http://img641.imageshack.us/img641/7346/img0017b.jpg
It's pretty bad and the whole trace is gone. I had to replace the drive with a 74 I had lying around.
How can I make sure this does not happen again? Someone on XBScene said to "check the traces with a multimeter." Well, the problem is I don't know what to check.
Topic: Exploded Lite-On trace (Read 3390 times)