Resistors are a very common item on printed circuit boards, appearing frequently in both analog and digital designs. Placing and removing them is a simple procedure, and a good way to learn to solder electronics. Replacing a resistor can produce surprisingly dramatic changes to a circuit, which can be instructive and an interesting way to modify existing devices. Instructions Preparation 2 Secure the circuit board to free your hands for the rest of the task. If you're removing a resistor, secure the board so that you have access to both sides at once. Otherwise, the board may rest, components down, on a tabletop, with some kind of weight on an edge or two to keep it in place. 3 Tin your hot iron by applying a small bead of solder to the tip. This will encourage heat conduction from the iron to the resistor's leads and the contacts on the board. Removal 5 Touch and hold the tinned iron to one of the two leads on the back of the board. 6 Wait a few seconds to heat up the joint. The solder surrounding the lead will change appearance and move slightly as it liquefies in response to the heat. 7 Pull out the lead you are heating from the opposite side of the board using the pliers. Make sure the lead is completely clear of the board. The other, unheated lead, will bend as you do this. 8 Heat the other lead and pull the whole resistor off of the board. 9 Clear out excess solder from the holes left by the leads using the desoldering braid or vacuum. The braid should be applied in between the iron and the hole, while the vacuum should be applied to the opposite side of the board from the iron. If using a vacuum, activate it when the solder liquefies as in Step 4. If using a braid, simply heat until the solder flows into the braid, discoloring it and clearing the hole. Replacement 11 Insert the leads into the holes and push the resistor in until it is flush with the board. It does not matter which lead goes in which hole. 12 Touch and hold the tinned iron to one of the leads and its hole. 13 Wait a few seconds, then apply solder to the lead and hole with your other hand. Touch the solder to the iron only tentatively if it does not quickly liquefy. If the iron is properly tinned and is hot enough, the solder should not need to touch the iron. 14 Stop applying solder and remove the iron when the solder has flowed over and covered the joint. The solder should flow into, but not through the hole if the heat is applied properly. Be conservative; too little solder is better than too much. 15 Check both sides of the joint to make sure there is not excess solder on either side. Remove any excess using the braid or vacuum. 16 Solder the other lead in the same way as the first. 17 Trim the ends of the replacement resistor with the wire cutters.
1 Heat your soldering iron to around 374 degrees F. If you cannot easily determine the iron's temperature, start with a medium-high setting and adjust it as you practice soldering with it.
4 Identify the resistor you want to remove and find its two leads on the back of the board. The leads are the wires that connect the resistor to the board, and will be clipped short on the back of the board.
10 Bend the leads on the replacement resistor 90 degrees using the pliers. Try to place the bends in such a way that the leads will fit in the holes when the resistor is flush with the board.
