How to measure the transformer is good or bad?

How to measure the transformer is good or bad?
Measurement methods:

1, power off measurement:

1 Transformer is composed of two sets of coils. Each set of coils is wound by a wire, so the resistance value can be judged as good or bad. The 220V input line is generally red line. The resistance value of this group of wires cannot be too small. When using the multimeter, the short circuit can not be short-circuited. If the short circuit is close to 0Ω, it will be broken. The red line generally has a resistance value of 30 Ω to 200 Ω. The larger the power, the smaller the resistance value and the smaller the power value.
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2 If there is an open circuit, check the fuse. If the fuse is good, the internal line of the transformer input coil is broken. The output line is usually black line or other color, and the resistance is close to 0Ω. If the resistance is large or the circuit is broken, the line is broken.

2, power measurement:

Power on the multimeter AC AC test output line, if there is voltage output and stable is good, such as no voltage output or output voltage is not regulated is broken.

3, visual inspection:

Look at the appearance of the transformer, there is no trace of high temperature burnt, if there is a appearance of high temperature deformation is burned out.
This article is from allicdata.