Content of the Technical Meeting on August 29, 2011 at Beijing Panasonic Washing Machine After-sales Service Center
Data source: Beijing Panasonic Washing Machine After-sales Service Hotline http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3444727.
For top-loading fully automatic washing machines that use a DC electromagnet, the electrical load component connected during drainage is the DC electromagnet. The popping sound during drainage is generated by the DC electromagnet. During inspection, it can be found that the electromagnet continuously engages and releases. According to the analysis of the electromagnet's working circuit, this fault is due to an open circuit in the holding coil of the electromagnet.
When the pulling-in coil is normal but the holding coil is open-circuited, when the electromagnet is powered on for the first time, the rotary contact point controlled by the armature is connected, so the circuit inside the electromagnet is connected, allowing the armature to be pulled in and the drainage valve to be opened. However, after the armature is fully engaged, it causes the rotary contact point to disconnect, cutting off the current to the electromagnet, thereby losing its electromagnetic attraction to the armature. As a result, under the action of the spring inside the drainage valve, the armature is pulled out, and the drainage valve closes. But as soon as the armature leaves the button on the electromagnet, the rotary contact point automatically reconnects, reconnecting the circuit inside the electromagnet, allowing current to flow through the pulling-in coil again. The electromagnet regains its suction force and pulls the armature back in, reopening the drainage valve. This cycle repeats itself, with the electromagnet alternately engaging and releasing, producing a continuous popping sound. The drainage valve also alternates between opening and closing, preventing normal drainage. If this continues for a long time, it may cause the electromagnet to overheat and burn out.
The method to fix the fault is to replace the DC electromagnet.
Continuous popping sounds are heard during drainage from Panasonic top-loading washing machines using a DC electromagnet, with very little drainage.