How To Identify a Burnt SMD Component? (Every SMD Type)

Printed circuit boards are used in nearly every device today. The PCB contains many SMD components like resistors, capacitors, and diodes. If any of these components fail, it can affect the whole circuit. So, how to identify a burnt SMD component?

How To Identify a Burnt SMD Component?

It’s not an easy job to identify a burnt SMD component, because SMD components are many and different such as capacitors, resistors, and inductors, these are only the passive components in the PCB. In addition, there are the active components, for example, the diode, every component has its method:

How To Identify a Burnt Resistor?

First, you have to know what a resistor looks like, all resistors have the same looks from the outside. They are tube-shaped with colored stirps on them; it also has a connection on each side. So, to find the value or identify the burnt resistor, you have four methods, and you can follow anyone of them.

Method 1

  1. Remove the resistor coating.
  2. Clean the burn trace.
  3. Measure the resistance of the resistor from the burnt side to the other one.
  4. Again, measure the resistance but this time from the good side to the burnt one.
  5. Sum the two values you got.
  6. It’s approximately the value of the resistor.
  7. You can add a small value to make it more accurate.

Method 2

  1. Measure the voltage drop across the resistor using a multimeter.
  2. Then measure the current that passes through the resistor.
  3. Calculate the wattage by multiplying the current and the voltage values.
  4. The wattage of the burnt resistor will be less than the resistor you replace.

Method 3

In this method, you would have to know the outage voltage of the circuit. In addition, a couple of resistors have the same burnt resistor wattage.

  1. Set a high resistance value, then temporarily connect the resistor you have instead of the burnt one.
  2. Measure the circuit’s output voltage of the circuit. If you obtained the same voltage as you thought in the beginning. Then, you have the resistor value.

Method 4

Another method you can use is to read the value of the resistor printed on the circuit board. However, this method doesn’t always work because the value could not be written on the PCB, but if you know that your board has the values on it. Then, this method can save you a lot of time.

How To Identify a Burnt Capacitor?

You can know that your capacitor is burnt or leaky through the dielectric plate. The plate resistance would have decreased so that the capacitor could generate a current. The main reason for that is dielectric plate chemical degradation.; it will also generate unusual heat due to capacitor degradation.

As a result of this heat, the capacitor’s body could be cracked up. Which breaks the connection and/or starts up a fire in the dielectric plate or the coat. The electrolytic capacitor has metal cans, and when it becomes leaky, the dielectric plate expands, which generates pressure on the metal cans.

When the increases, the metal cans explode or burst, they release pressurized corrosive or smoke electrolytes. To avoid these consequences, you can install the can of the capacitor with a pressure relief opening or vent. If you have ever seen a large electrolytic capacitor leaking or burnt, you would see the chemical corrosion or smoke.

Source

How To Identify a Burnt Diode?

Diodes are small components found in any PCB, and they allow the current to pass in one direction only. This happens because the diode has a high resistance on one side, meanwhile, the other has a low resistance. The diode is made from a semiconductor material like silicon; you can know if it burnt or not through any of these three methods:

Method 1

  1. Turn off the power of the diode. Testing a diode while it’s still connected to power is very dangerous. Besides, if the diode is turned on, this will give an accurate result. So you have to remove the diode or turn off the circuit’s power, and also, don’t forget to discharge the capacitors to avoid shocks.
  2. Use an analog multimeter. Adjust the multimeter to the low resistance of about 1 KΩ; this will allow the flow of a small current through the diode, the low current protects the diode from overloading. 
  3. Connect the multimeter leads. Grab the red multimeter lead and connect it to the cathode, then, grab the black multimeter lead and connect it to the anode. The anode is the positive one, and the cathode is the negative one (which has silver stripes). Now, there will be a current generated and passing through the diode.
  4. Observe the multimeter’s reading. The reading should be between 1 Ω and 100 Ω if it’s a forward biased, meanwhile, the resistance will be infinity if ut’s backward biased. In case of any different than that in the reading, you need to replace the diode.
  5. Adjust the multimeter again. Readjust your multimeter to the high resistance of about 100 KΩ. 
  6. Reverse the multimeter’s leads. Connect the red multimeter lead to the anode, then, connect the black multimeter lead to the cathode. Now, the diode is reversed, so there is no current flowing through it. 
  7. Observe the new reading. There should be an OL (open loop) symbol, or the resistance is infinity, however, if the diode gives a low resistance, you should replace it.

Method 2

  1. Disconnect the circuit from any power. You can either do this by causing a break in the circuit or removing the power source (battery). In addition, you have to discharge the capacitors; this will make you avoid any shocks probability. You can do this by touching the capacitor’s ends together. 
  2. Adjust your multimeter to diode mode. This mode creates a 2mA current to pass through the diode. The current will not override the diode and still produces a reading, the mode can have a small diode mark on the multimeter.
  3. Connect the multimeter leads. Grab the red multimeter lead and connect it to the cathode, then, grab the black multimeter lead and connect it to the anode. The anode is the positive one, and the cathode is the negative one (which has silver stripes), the current will be in the forward direction.
  4. Observe the multimeter reading. The reading should be between 0.5 and 0.8 volts; this means that the diode is working properly and is healthy. If the reading is other than that, your diode is bad, and you should replace it.
  5. Reverse the multimeter’s leads. Connect the red multimeter lead to the anode, then, connect the black multimeter lead to the cathode. Now, the diode is reversed.
  6. Observe the new reading. There should be an OL (open loop) symbol, or the resistance is infinity, however, if the diode gives a low resistance, you should replace it.

Methode 3

  1. Turn off the power of the diode. Testing a diode while it’s still connected to power is very dangerous. Besides, if the diode is turned on, this will give an accurate result. So you have to remove the diode or turn off the circuit’s power. Also, don’t forget to discharge the capacitors to avoid shocks.
  2. Adjust your digital multimeter to resistance (ohm) mode. Set the resistance to a low value of about 1 KΩ. 
  3. Connect the multimeter leads. Grab the red multimeter lead and connect it to the cathode, then, grab the black multimeter lead and connect it to the anode. The anode is the positive one, and the cathode is the negative one (which has silver stripes); the current will be in the forward direction.
  4. Observe the digital reading. The reading should be less than 100 Ω, which means the current is flowing correctly. 
  5. Adjust the multimeter again. Readjust your multimeter to the high resistance of about 100 KΩ. 
  6. Reverse the multimeter’s leads. Connect the red multimeter lead to the anode, then, connect the black multimeter lead to the cathode. Now, the diode is reversed.
  7. Observe the digital reading. There should be an OL symbol or infinite resistance. If you have any resistance reading, then your diode is bad, and it would be best if you replaced it.

Conclusion

To sum up, you can identify any burnt SMD component, even if it is not that easy. First, you should try to see if the shape matches any other component in the circuit. Then, after knowing if it is a passive component like resistors, capacitors, or inductors. Or it’s an active component like a diode, and you can follow each component method.

Burnt components can leak or burst into a fire like capacitors; you have to be always careful and do maintenance as soon as possible. When a component bursts, the damage could reach other nearby components too. It would be best to repair it or replace it before this happens. 

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