How to Replace & Solder Resistors on a Circuit Board?

PCB Assembly Soldering

Resistors are the essential electrical components for printed circuit boards (PCBs). The PCB manufacturer  places resistors to resist the flow of current in the circuit. They attach them to the board by employing solder irons. It is a straightforward operation. Yet, when the resistors malfunction, it requires quick replacement and re-soldering on the PCBs.

We understand your concerns. Therefore, we have brought an ultimate guide to let you know the steps of desoldering, replacing, and soldering the new resistors on the PCBs. This article discusses the essential tools, techniques, and strategies for replacing and soldering the resistors on the circuit board.

Tools required for Soldering

To complete the simple soldering job, all you need is the following pieces of equipment:

  1. Soldering iron

Soldering iron is a pencil-like tool and is mainly used to provide heat to melt the solder. It consists of various parts, making it comfortable and safe to use. The PCB manufacturers use solder guns for major soldering.

  • Solder wire

Solder wire is a metal alloy that is heated up to create a permanent bond between the components and comes in diameters of 0.8mm and 1.5mm. Lead-free rosin core solder is commonly used for soldering big electrical components on the PCB.

  • Solder flux

The manufacturers generally use solder flux to clean the surface  of the PCB before the soldering process. It is applied to remove the oxides and impurities from the metal surface of the printed circuit boards and strengthen the joints.

Steps to replace the resistor:  

Following are the steps to replace the damaged resistor from the PCB:

  1. Insert the wire leads of the resistor into the holes and bend them 90 degrees along the back of the circuit board. So the resistor holds the place.
  2. Place the tip of the soldering iron beside the soldering wire tentatively and press gently.
  3. Melt only the required solder wire and remove both the soldering iron and wire as soon the solder covers the joint and the resistor acquires the position.
  4. Repeat the same procedure for the other lead.
  5. Remove excess solder across the joints with the help of soldering iron.

Techniques of Soldering Resistors on the PCB:

  1. Preparation
  2. Heat the soldering iron or gun up to 400 degrees Celsius (or 673 degrees Fahrenheit) and handle it carefully.
  3. Tin the soldering iron tip by applying a small amount of solder to ensure heat conduction.
  4. Stabilize the circuit board in the position. So, you have access to all sides of the circuit board.
  5. Uprooting
  6. In case of replacement, recognize the defected resistor and find the wire leads of the defected resistor at the back of the circuit board.
  7. Place the tinned iron tip on one of the wires leads and hold it for a few seconds to heat up the joints until the solder surrounding the joint starts to melt.
  8. Repeat the task for the other wire lead.
  9. Detach the resistor off the circuit board safely. So, it does not damage the circuit board.
  10. Open the holes blocked by the solder with the help of heated soldering iron. Push the tip of soldering iron through the closed holes and simultaneously enlarge the holes.
  11. Use the soldering iron tip to wipe the excess solder from the components on the circuit board.


Other PCB resistor related knowledge

What is 0-ohm resistor

A  zero-ohm resistor, also known as a 0-ohm link, is a special purpose resistor. A 0-ohm resistor is not 0 ohm (that’s what superconductors do). A typical value is about 0.05 ohm due to the resistance value of a 0-ohm resistor having the same error accuracy as conventional chip resistors.

What are the functions of 0 Ohm Resistors

It has no function on the board, but it is only for debugging easily or design factors.

As the current loop when connected across

When the electrical ground plane is separated, the signal’s shortest return path is broken. At this time, the signal loop has to be detoured, producing a large loop area, and the influence of the electric field and the magnetic field becomes stronger, and it is easy to be disturbed/disturbed. It can provide a short return path and reduce interference by connecting a 0-ohm resistor across the partition

If a certain line is not used, do not paste the resistor directly; it can be used as a jumper.

When the parameters are uncertain, 0 ohms instead. When debugging, know the parameters and replace them with specific values.

Convenient wiring

In the PCB layout and wiring stage, sometimes there is a situation where the wiring always fails, especially when the circuit board area is small, there are many connections, and the number of layers is small. Suppose you encounter a connection that needs to be wound around a large circle to connect. In that case, you can consider whether you can easily skip the wire in front of you by connecting a zero-ohm resistor instead of winding a largecircle.

When measuring the current consumption of a certain part of the circuit, you can remove the 0ohm resistor and connect an ammeter, which is convenient for measuring the current consumption.

It can be used as an inductor or capacitor under high-frequency signals. Inductors are mainly used to solve EMC problems. 

Single-point grounding and each becomes an independent system).

Fuse function

Single-point grounding of analog ground and digital ground.

Configuration circuit

Generally, it does not set jumpers and DIP switches on the product, but customers will disturb the settings and cause misunderstandings. So, 0-ohm resistors are used instead of jumpers to be welded on the board to reduce maintenance costs.

The vacant jumper is equivalent to the antenna at high frequency, and the chip resistor is effective.


The electrical components combine to make efficient working PCBs. Resistors and capacitors are essential to determine the PCBs functionality. So, it is significant to keep them up to date. This article provides the steps to replace and solder the resistors to ensure optimum performance. If you are also concerned about this, this article is for you.