If the Diode PCB is damaged, the original model can be seen clearly, just replace it with a diode of the same model.
If you can’t see the model or the model is not marked, you can generally replace it according to the function of the diode in the circuit.
How to determine the model number?
If you see four diodes on the Diode PCB, then it is a rectifier diode.
Four rectifier diodes are used to form a bridge rectifier circuit to convert alternating current into direct current.
Bridge rectifier circuit composed of rectifier diodes
Generally, the mark on the circuit board will have its model, and components of the same model can be replaced through observation.
The rectifier circuit utilizes the unidirectional conductivity of the rectifier diode, which can convert alternating current with alternating directions into pulsed direct current with a single direction.
First of all, let’s talk about several commonly used diodes:
- led
- rectifier diode
- switching diode
- Zener diode
led
If it breaks, just replace it with one of the same kind.
But pay attention to the withstand voltage and maximum current of the LED, otherwise it will be easily damaged again.
You can use the diode gear of the multimeter to detect whether the LED is good or not. The red test lead is connected to the positive pole of the light-emitting diode, and the black test lead is connected to the negative pole of the light-emitting diode.
If it glows, the diode is working properly.
It is generally used for circuit indicator lights. If the circuit works normally and the indicator light is off, it means that the light-emitting diode is damaged.
rectifier diode
How to determine whether the diode on the circuit board is a rectifier diode?
Generally it is used in rectification and filtering circuits.
There are several capacitors next to the diode, which means that the diode is a rectifier diode.
It is damaged and the circuit will not work properly!
switching diode
Switching diodes are generally glass-encapsulated and are often used to protect various low-current components.
When it is found that the glass-encapsulated diode on the circuit board is damaged, the type and type of the damaged diode can be determined according to the symbols below the components on the circuit board, and it can be replaced directly.
Zener diode
This kind of diode looks very similar to a switching diode. Without professional tools, it is impossible to distinguish between a Zener diode and a switching diode.
However, it can be inferred by observing the circuit structure and the role of components in the circuit.
The glass-encapsulated diodes connected to the power supply are generally Zener diodes, and the other places are switching diodes.
Switching diodes are ordinary diodes that use forward conduction and reverse cutoff to play a switching role, while Zener diodes mainly work in a reverse breakdown state.
Switching diodes are suitable for rectification, reverse voltage protection and other circuits, and voltage regulator tubes are mainly suitable for voltage stabilizing circuits.
The best way
Find the circuit schematic diagram, and the model of the product can be obtained from the circuit schematic diagram.
It is the most accurate and fast to analyze according to the graph!
You can also infer its function according to its position on the circuit board, and check the marked symbol or model on the Diode PCB.
English