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how to modify laptop power jack? Answered

So hey there instructablers! I had a laptop with a loose power jack and a bad battery that was working perfect but when i moved the charger a little bit it was losing contact so it was turning off. One day i decided to rip apart the laptop and see if i could fix it. I opened it only to find that the jack had completely come out of the board! So i came up with the idea to solder the charger wires directly to the board without a jack. It seems possible, right? But i got into a problem! I couldn't find which of the remain lead was the positive and negative. I have attached a photo and i have circled the jack lead and number them. If anybody could help me buy explaining me which lead does what i would appreciate it! Thanks in advance!

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-max-

4 years ago

It is pretty much universal these days that the ground, or negative terminal is connected to large traces and flood-filled areas of the PCB. Do you see that 5, 3, 2, and 1 is all connected together and it is all one node on the board? That is just a thick trace, and it is likely the positive. I cannot tell where it goes off to in the picture, but it does not completely fill the darker areas on the board, like Pin 4 is the only one not connected like the rest. This is the opposite polarity.Flip the board upside down and look to see if that is part of a large ground plain or flood filled area.

Reverse polarity is one of the easiest method to completely destroying electronics, so if you really want to know, get a multimeter and test out the various points to see if they are connected to, say, the metal shielding (metal boxes that are soldered to the circuit board) ot even the metal case around the USB connections and the ports, and/or plug in the power suppply and measure the voltage between pi 4 and the rest. I suspect pin 4 is the ground, or negitive.

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mpat.man.3-max-

Answer 4 years ago

Oh man thanks very much for your answer! But i think its already late...i am 90% percent sure the board is totally fried. Either from static or from reverse polarity as you said. Forget it, it was an old man he had already lived his life!The good thing was that I took his organs to use them on a future project! Again thanks for your reply :)