Good Soldering Technique for Changing Parts on a Printed Circuit Board
You will need some solder and a soldering iron. First make sure your soldering iron tip is tinned. To tin your soldering iron, Clean the tip with a wet sponge or if the tip is pitted you will need to file it to get it into shape. Then when the iron is hot apply a small amount of solder to coat the tip. Wipe off the excess solder leaving an even coating on the tip. This will make a good heat transfer to the soldering joint.
Next, something to solder, like a printed circuit board with components on it. If you need to change a component, you will need a solder sucker or de-soldering wick to remove the old component. A soldering iron stand is nice to have to safely heat up your soldering iron, but not a must if you are careful. Heat up your soldering iron phone repairs. Then melt the solder holding the part you want to remove. When the solder is molten, take your wick or de-soldering pump and remove the solder. If the hole on the circuit board is not completely removed you can take a tooth pick and iron to clean it out. Remember that a lot of components like semiconductors, Transistors and Integrated circuits cannot take a lot of heat without destroying the part, also excessive heat will lift the pad on your printed circuit board. If you lift the pad on the board you will have to run a jumper to the lifted point. Now take your new component and place in the holes and bend the leads outward to hold it in place. Take your soldering iron and touch the point to be soldered. Place the solder wire to the joint. Let the solder melt and surround the lead. Hold the soldering iron just a few more seconds to give the rosin flux time to clean. Now you should have a good solder joint.
Now you can reinstall the printed circuit board into the case or enclosure you removed it from. When you reinstall the printed circuit board make sure there are no points where the circuit solder joints can short out or ground to the case. There are a lot of transistors and Integrated circuits that generate a lot of heat. Make sure to reinstall the heat sinks and cooling fans. To get maximum cooling you will need to coat the heat sinks with silicone grease before installing. Thanks for looking.