TESTING COILS, INDUCTORS and YOKES

Coils inductors and yokes are just an extension of a length of wire. The wire may be
wrapped around a core made of iron or ferrite.
It is labeled "L" on a circuit board.
You can test this component for continuity between the ends of the winding and also
make sure there is no continuity between the winding and the core.
The winding can be less than one ohm, or greater than 100 ohms, however a coil of
wire is also called an INDUCTOR and it might look like a very simple component, but it
can operate in a very complex way.
The way it works is a discussion for another eBook. It is important to understand the
turns are insulated but a slight fracture in the insulation can cause two turns to touch
each other and this is called a "SHORTED TURN" or you can say the inductor has
"SHORTED TURNS."
When this happens, the inductor allows the circuit to draw MORE CURRENT. This
causes the fuse to "blow."
The quickest way to check an inductor is to replace it, but if you want to measure the
inductance, you can use an INDUCTANCE METER. You can then compare the
inductance with a known good component.
An inductor with a shorted turn will have a very low or zero inductance, however you
may not be able to detect the fault when it is not working in a circuit as the fault may
be created by a high voltage generated between two of the turns.
Faulty yokes (both horizontal and vertical windings) can cause the picture to reduce in
size and/or bend or produce a single horizontal line.
A TV or monitor screen is the best piece of Test Equipment as it has identified the
fault. It is pointless trying to test the windings further as you will not be able to test
them under full operating conditions.