What's wrong with the cooker?
1. First locate the base of the two drive tube and see which foot is attached to the LM339.2, according to the internal block diagram of LM339, you can see the other two feet, and these two feet must have one to the MCU, and to the MCU, this foot is the input pin of the PWM pulse signal.3, find the foot after the problem is simple, the next step can disconnect the diode after measuring MCU output PWM pulse signal whether to determine the fault location. Here, the other specific testing procedures will not have to say, I believe that a little basic knowledge of friends know how to check.4, there is a key point, namely (1 and 5 feet), 1 feet and 6, 7 feet related, such as 6, 7 feet voltage changes, then 1 feet voltage will change, PWM pulse signal will be affected. The most common is the problem, is between 6 and 7 polyester capacitor feet (2A222J) caused by bad disorderly pot.
For the induction cooker, I classified the common faults into the following three categories:1, 300V filter capacitor is not good, causing the main voltage is too low, so that the voltage detected by the synchronous circuit is not normal.2, synchronous circuit of high power resistance deterioration or open circuit, resulting in abnormal detection circuit.3, PWM pulse signal is abnormal and not check pot. (check method of PWM pulse is simple, the forum also has introduced, is to find a small transformer, with a light emitting diode, in the primary on the heating plate of the electromagnetic oven after boot, LED flash PWM pulse is normal, no response is not normal)
Maintenance method of electromagnetic cooker without checking potThe electromagnetic oven repair inspection pot, is an easy job to do things to proficient, but beginners often feel difficult to find, and easily mistaken for MCU damage. In response to this situation, I have accumulated a little experience that we usually hear, but also in order to be able to communicate with you more, and raise their own technical level.
