If you have problems with your circuit board, don't worry - you're not alone. Many people have issues or even don't know about troubleshooting PCBs. It doesn't matter if you're a beginner or a professional; there must be a point when your circuit board starts malfunctioning. 90% of circuit boards are made up of almost the same components, so no rocket science is required to test them. Here, I will tell you how to troubleshoot circuit board and save some bucks.
The most important thing to remember when troubleshooting your circuit board is that you need to take your time and be patient. Rushing through the process will only result in more mistakes and wasted time.
What are circuit boards, and What do they do?
Circuit boards are everywhere, from your cell phone to the washing machine. Every electronic device has a PCB. They are the heart of every electronic device as they hold all the components together and provide connectivity between them.
PCBs have different layers, each with its own role in connecting the different parts of the circuit. The top layer is where most of the components are soldered, and it's also known as the component side. The bottom layer is where the tracks or traces are found. Such tracks are basically, copper pathways that connect the different components on the board.
Moreover, in between these two layers is a dielectric material, insulating the different parts of the circuit and preventing electrical shorts.
Three Best Methods to troubleshoot circuit board
Three different methods can be used to troubleshoot your circuit board.
1. Physical Inspection of Circuit Board :
Most of the circuits with overheating or short-circuiting issues can only be rectified by physical inspection. You can easily see defective printed circuit boards with a visual inspection, but the discrete active components, burnt components, and missing components are the real trouble.
- If you see any burnt or blackened area on the PCB, it indicates overheating.
- In such a case, you should check for the proper wiring around the circuit board and also check if all the components are mounted correctly.
- You can see the burnt or blackened area around the tracks if any shorts are in the circuit. These shorts can be due to improper soldering, damaged tracks, or other component issues.
- Therefore, if you see any of the above issues, you should check the corresponding component for any damage and the wiring and soldering around that area.
2. Use of Multimeter to troubleshoot Circuit Board:
A multimeter is a most trusted and widely used equipment while troubleshooting any electronic circuit. If you don't have a multimeter then click here to get best multimeter for electronics use.
It can measure the voltage, current, and resistance in a circuit. You can test your circuit board in the off position or in the on position. You should check components like capacitors, diodes, and resistors if it's off. You should check the voltage at different circuit points if it's on.
Continuity test of the circuit board:
- If you want to check for any open or short circuits, you should use a multimeter in the continuity mode.
- For this, you have to connect one probe of the multimeter to one end of the circuit and the other probe to the other end.
- If the multimeter beeps, it means there is no open circuit; if it doesn't beep, then there is an open circuit.
Voltage test of circuit board:
In an electrical circuit, the power supply voltages help troubleshoot faulty PCB. Because the voltage draw among components varies as per PCB manufacturing designs.
- You can also use a multimeter to measure the voltage in different parts of the circuit.
- To check voltage, rotate the knob to AC or DC voltage mode (depending upon your source voltages).
- Now set the ranges knob to a higher value and then touch the probes, the black probe to negative or neutral and the black probe to the positive terminal.
- If the multimeter shows any value other than 0, there is some voltage in the circuit.
3. Use of Rosin Pen or Flux Smoke:
- Personally, I love this method, as it is the easiest one. All you need is rosin or flux meter. It can be a rosin pen or your soldering iron smoke.
- First, put the rosin pen's smoke on the circuit board. It will make a white fume-like layer on the board.
- Now turn the circuit power on; if it's an SMD circuit and you see any component turn which melts the white flux smoke, it means that the component is heated or faulty, and you have to check it.
- This method is mainly used in manufacturing, but you can also use it while troubleshooting.
- In addition to this, you can do circuit board testing with a logic analyzer, multimeter or lcr meter. But the logic analyzers are a bit more advanced, and I don't recommend them for beginners as they are on the expensive side.
Components on Circuit boards (Parts of PCB)
Before jumping on to PCB or Circuit board troubleshooting, you must clearly understand the different components used on a circuit board and what they do.
PCB or Printed Circuit Board
First and foremost is the Circuit board itself. A PCB is a thin board made of fibreglass, composite epoxy, or other laminate materials. They are designed to support and electrically connect electronic components using conductive tracks, pads, and other features etched from copper sheets laminated onto their surface.
They are passive two-terminal electronic components that resist the flow of electric current by producing a voltage drop across their terminals in proportion to the current. There are multiple types of resistors, like carbon resistors, metal film resistors, etc. Moreover, you can see in the below-mentioned image what a resistor looks like.
They are passive two-terminal electrical components used to store energy in an electric field. A capacitor is composed of two conductors separated by a dielectric (insulator). Mostly capacitors are used to hold a charge for a very short interval of time. The purpose of this storage is to filter or rectify the current. Paper capacitors, dielectric capacitors, electrolytic capacitors, and ceramic capacitors are some types of capacitors. Below, I have mentioned a few types of capacitors with their images.
Diodes are the most basic semiconductor devices. Semiconductors are materials that can connect and conduct electricity under some conditions and act as an insulator under other conditions. Diodes allow an electric current to flow in one direction only. They're used in circuit boards used as bridge rectifiers, voltage regulators, signal limiters, etc.
They are active three-terminal semiconductor devices used to control the flow of electric current. A transistor can be used as an amplifier or a switch. Bipolar junction transistors (BJT), field-effect transistors (FET), and Darlington transistors are some types of transistors.
Integrated Circuits (ICs):
ICs are the most complex part of a PCB. They are tiny electronic circuits consisting of transistors, diodes, resistors, and capacitors. ICs are classified into analog or digital based on their function. Digital ICs are used in microprocessors, RAM, ROM, and other digital integrated circuits. Moreover, Analog ICs are used for linear amplification, active filters, etc.
No controller or circuit board can be completed without a relay. A relay is an electrically operated switch that can control the current flow in one circuit by opening or closing the contacts in another. Relays are consists of electromagnet (coil), a switch, and a set of contacts. Its applications are countless.
Other components are also on the circuit boards like LEDs, Mosfets, IGBTs, fuses, etc. But those mentioned above are the most important and widely used components on a circuit board.
Now that you know about the different components let's jump into troubleshooting your circuit board.
Possible Faults and their remedies while troubleshooting circuit board
Wiring faults are the most common type of faults. These faults can be due to improper soldering, loose connection, or damaged tracks. There must also be a short circuit if there are any wiring faults. The wiring faults can be rectified by proper soldering of the tracks and also by replacing the damaged tracks. After proper wiring, you should also check the component in the series circuit before initializing the circuit properly.
If the circuit board is not clean, it can also cause some faults. The accumulation of dust on the tracks and components can lead to a short circuit. The circuit board should be cleaned properly before starting the troubleshooting process. You can use compressed air to clean the tracks and components.
Replacements of components:
If you see any faulty components, it can also cause some faults in the circuit board. Sometimes it's even possible that your card will not be on. The damaged or faulty component should be replaced with a new one.
Replacement of Circuit board:
If the circuit board is damaged beyond repair, it needs to be replaced. The only remedy for a damaged circuit board is to replace it with a new one.
Safety Guide (about how to Troubleshoot Circuit Board):
Electricity is not a toy; one should be very careful while working with it. One should always follow the proper safety measures while working with electricity. Some of the safety measures are:
1. Always work in a well-ventilated area.
2. Always wear proper safety equipment like gloves, glasses, and masks.
3. Never work alone; always have someone with you who can help you in case of an emergency.
4. Never work with wet hands or feet.
5. Always disconnect the power source before working on the circuit.
6. Never work on a live circuit.
7. Always use insulated tools.
8. Be extra careful while working with high-voltage circuits.
9. Always follow the manufacturer's instructions carefully.
10. Keep your work area clean and organized.
This guide will answer your questions if you don't know how to troubleshoot circuit board. The troubleshooting process can be divided into two parts: Isolation and rectification of the fault.
Both of these processes are important and should be done carefully. The most common type of fault is wiring faults; these can be rectified by proper soldering of tracks and replacing the damaged tracks.
If any of the components are damaged or faulty, it can also cause some faults in the circuit board; the damaged or faulty component should be replaced with a new one. If the circuit board is damaged beyond repair, it must be replaced. So, always follow the proper safety measures while working with electricity.