How to judge the quality of microwave oven transformer

The transformer for microwave ovens is a booster transformer (see attached drawing). There’s not much special about transformers compared to what we usually see. It is also composed of primary windings and secondary windings. The primary winding has one and only one set of voltages connected to 220V AC mains. Secondary has two winding two groups of voltage: a group of voltage is: about 4V filament heating voltage.

The other set of voltages is the high voltage of 2100V to power the double voltage rectifier. Note that one end of the voltage extraction point is connected to the microwave oven transformer core. One piece is the one that comes out of the plug. Galanz microwave oven through the plug out end insurance, Haier most microwave ovens are also plug out end warranty. Warranty specification 2000V0.75A. LG microwave ovens cancel this insurance, directly from the transformer outlet plug to the high voltage rectifier end.

Know the microwave high voltage transformer structure, it is easy to judge its good or bad.

Detection method:

1. Detection and judgment of no power: use a multimeter to measure resistance. The resistance of the primary end is 2 ohms, and the resistance of the secondary filament is nearly short. High voltage winding resistance value 80 ~ 120 ohms. Different transformers differ significantly.

2. Power detection judgment: connect the primary to 220V AC mains, see whether the secondary voltage is within the range. Filament about 4V, high voltage 2000V, 2000V here is difficult to measure. Our common multimeter measurement voltage is not so high. Preliminary judgment may be made by drawing out the arc. It takes experience. It can also be judged by measuring no-load current. Microwave oven with transformer control current about 4A.

3. By using the principle of series circuit voltage division, to expand the range of the multimeter, it can be very convenient to measure the high voltage transformer high voltage by energized method.