How to repair the power tube of the induction cooker repeatedly burned

What is the reason for the repeated burning of the power tube in the induction cooker?

There are many reasons for induction igbt, and it is recommended here that it is best to have an oscilloscope for repairing an induction cooker. In this way, the fault can be accurately judged.

Here are several hidden problems of induction cooker explosion IGBT.

One; The voltage difference between the two ends of the synchronous circuit is abnormal (there are 3 5 resistors of 300k 680k 2 watts at both ends of the coil, connected to one of the 339 comparators). The voltage is about 3V 5V when standby, and about about when working.

Two; The pulse width of the excitation circuit is too wide, spikes, clutter, etc. (if the pulse width is too wide, use an oscilloscope, and when the pot is put on the pot, the waveform change of the oscilloscope waveform at the moment when the pot is removed cannot exceed two bars on the oscilloscope).

Three; Poor heat dissipation.

Four; Problems in the design of the circuit board itself (main problems: unreasonable ground wire, poor inductance and capacitor matching of the coil reel) are difficult to solve.

Five; Using the early Fairchild FGA25N120, FGA15N120 series IGBT (IGBT suffix number AN and AND) induction cooker, especially for this IGBT with high-power induction cooker, the circuit design is slightly poorly matched, it is easy to cause IGBT to overheat and burn out.

Six; Generally, there are many bad capacitors, especially rectifier filter capacitors"5uf/275v~x2(400vdc)", reverse stroke, resonant capacitor, both will threaten the power switch tube, a better furnace will have a protection function for the former, for the latter, the power switch will generally be burned, so when you encounter the furnace of the burning tube, you must first check whether the capacitor has an open circuit, because the two capacitors often work in a high-temperature environment, easy to reduce the capacity or open circuit, leakage.

You should mainly check whether the three voltages are normal.

The protection circuit is burned out, that's right.

The power tube of the induction cooker often burns out due to a variety of factors, such as the unreasonable circuit design of the induction cooker, the unstable power supply voltage, and the use time for too long. If you want to repair the power tube of your induction cooker, you can take the following steps:

1.Check the circuit design.

First of all, it is necessary to check whether the circuit design of the induction cooker is reasonable. If the circuit design is not reasonable, it will cause the power tube to exceed its standby volt tolerance range, which will lead to the burnout of the power tube. When checking the circuit design, special attention needs to be paid to whether there are problems such as overvoltage or short circuit.

2.Check the power supply voltage.

Secondly, you need to check whether the power supply voltage is stable. If the supply voltage is unstable, it will also cause the power tube to burn out. When checking the power supply voltage, you can use a digital multimeter to measure and solve the problem of unstable power supply voltage in time.

3.Replace the power tube.

If factors such as circuit design and power supply voltage have been ruled out, it is likely that there is a problem with the power tube itself and a new power tube needs to be replaced. When replacing the power tube, special attention needs to be paid to the model and specification of the power tube to ensure that the power tube can operate normally.

4.Check the heat dissipation.

Finally, you also need to check the heat dissipation of the induction cooker. If the heat dissipation of the induction cooker is poor, it will also lead to the burning of the power tube. Therefore, it is necessary to pay attention to the heat dissipation problem when using the induction cooker, and you can clean the heat dissipation port and heat sink of the induction cooker in time to ensure that the heat dissipation effect of the induction cooker is good.

To sum up, in order to repair the power tube of the induction cooker, it is necessary to consider a variety of factors, such as circuit design, power supply voltage, power tube itself, etc., to find out the root cause of the problem and take effective measures to solve it. At the same time, it is also necessary to pay attention to the heat dissipation of the induction cooker in daily use to avoid overheating of the power tube, so as to prolong the service life of the induction cooker.

When using an induction cooker, there are many reasons for the damage of the power tube of the induction cooker, which are divided into two categories, one is sudden damage, including short circuit between the poles and short circuit of the electrode, and the other is gradual failure, including the gradual decline of cathode emission, the instability of parameters beyond the allowable value range, etc. What should I do if the power tube of the induction cooker is broken? You may wish to read on:

Sudden damage. 1. Interpolar short circuit: mainly caused by freely moving conductive particles.

The main reason for the appearance of these particles in the tube is that the inspection process and manufacturing process of the power tube parts are not perfect, which leads to the conductive particles falling on the tube die during vibration, thus causing a short circuit. If the power tube is broken as a result, it needs to be replaced.

2. Circuit breaking: abnormal conditions in or near the welding points in the power pipe will also lead to failures, and the correct way to deal with them is to re-weld them or replace them directly.

Gradual failure. 1. Cathodic senescence: It is an extremely complex problem, but it can be easily solved as long as you have a deep understanding of the physical processes that occur when the power tube is working. Once the cathode is aged and the power tube fails, it needs to be replaced.

2. Parameter instability: In addition to the change of cathode emission performance will affect the parameters of the power tube, there are many factors. Once this happens, it is important to note that the surface of the gate can be plated with gold to alleviate it, or the gate can be pre-oxidized.

The reason for the repeated burning of the power tube of the induction cooker is the poor performance of the mains filter capacitor, the mains filter capacitor is generally 5 F, and the mechanism of damage to the gate tube caused by its poor performance is the breakdown of the gate tube caused by the spike pulse, and the poor performance of the capacitor will also cause the gap heating phenomenon when the voltage is slightly lower, and the reason for the repeated burning of the power tube of the induction cooker may also be related to the poor performance of the CPU, crystal oscillator and reset circuit and the main resonant capacitor.

<> the reason why the induction cooker burns the power tube: resonant capacitor, 5UF 400V filter damage or insufficient capacity. In the induction cooker, failure or poor characteristics will lead to the high frequency of the induction cooker LC oscillation circuit, which will cause damage to the IGBT tube, and when the other circuits are found to be abnormal, we must replace the two capacitors together.

This answer is applicable to most induction cooker brands such as Midea, Supor, Joyoung, etc.

The reason for burning the power tube of the induction cooker;

1) The performance of micro-resonant capacitance deteriorates. As soon as the machine is turned on, the IGBT tube is burned, and it is generally the resonant capacitor that is at fault, and it must be replaced, and sometimes its capacity is about the same, but it is actually useless.

2) Synchronous circuits, VCE voltage detection circuits, large resistance resistances, filtering, resonant capacitors, driving circuits, etc.

3) Poor contact of the power plug and plug-in spool connector will also cause irregular burning of IGBT tubes.

4) After repairing the induction cooker that burns IGBT tubes repeatedly, I generally do the following treatment (I have dealt with a few units last year, and I will return to repair at the end):

Method 1: Replace the 18V regulator diode at the G pole of the IGBT tube with one, and add one by yourself if the original machine does not have it.

Method 2: Adjust the output power to a lesser level, and the power supply current can be lower than 7A at the maximum power level, although this will affect its heating speed, but this is also a way to do it.