Bidirectional diode, bidirectional thyristor speed control – unstable motor speed
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A vacuum cleaner features a motor speed control circuit that uses diodes, triacs, and a variable resistor; once connected to a 220V power supply, the motor starts rotating at its lowest speed but does so in an unstable manner. Using a multimeter, it was found that the voltage applied to the motor fluctuates between 60 and 80V. Could someone with expertise help determine what the problem is? The bidirectional diode is DB3 X951, and the thyristor is BTA16-600B
This is generally a circuit design issue; it has nothing to do with bidirectional diodes or bidirectional thyristors. Those available on the market are all simple trigger circuits, chosen for cost reasons. Of course, when there is no other option, it is recommended to remove the potentiometer and check whether its range of variation is stable. If not, it’s better to replace it; if no replacement parts are available, dropping some engine oil in and rotating it repeatedly can usually work for a while.
The control circuit is relatively simple, making it difficult to meet the requirements for output voltage stability control and performance at low speeds. If low-speed control is required, it is best to choose a specialized control device as it is more reliable to use.
It is not a professional control device, but a dedicated automatic control device.
This control unit is for a Midea vacuum cleaner. It stopped working suddenly during use; it wouldn’t turn on anymore. After waiting for some time, it started working again, but the sound it made wasn’t normal. I checked and found that the thyristor was damaged, so I replaced it. I also replaced the start capacitor, but the rotation speed remains unstable, with intermittent buzzing sounds. I’d like to know what could be causing this issue I want to make some repairs; I can’t measure anything with a multimeter regarding the potentiometer. The bidirectional diodes haven’t been replaced, nor has the trigger capacitor.
It might be that the motor or the mechanical components are damaged or stuck. It’s possible to turn it around with effort. Check it out.
It might be that the motor or the mechanical components are damaged or stuck. It’s possible to turn it around with effort. Check it out.