Page 80 - Testing Electronic Components

With power off, remove the transformer from the board and perform a
resistance or continuity test on primary and secondary winding as shown
on the picture of transformer below. If there is no resistance or ohms
reading on the primary and secondary winding measured, suspect an open
winding and the transformer need to be replaced. The advantage of this
method is you are safe because no power is applied to the transformer.

The disadvantage is checking the resistance for ohms reading is not as
accurate as when you perform a ringing test mentioned on the third
method. A shorted primary or secondary winding is still checked well
under resistance tests. However the good news is when either the primary

or secondary winding developed a short circuit, it will usually produced a
bad smell and the transformer gets very hot on its core or casing.

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