There is a certain technique for determining short-circuited turns in transformers. Based on this method, the author made a device, the diagram of which is shown in the figure.
This device allows you to determine the health of the transformer by the Q-factor of the winding wound with a thick wire and with a small number of turns. It is especially effective to use the device for testing transformers with a ferrite core: TVS, TDKS, TPI, as well as vehicle ignition coils. The device operates in the frequency range 0.37 ... 24 kHz. The tested transformer is connected to terminals X1, X2. By manipulating R1 and toggle switches S1, S2, they are tuned to resonance. If it is possible to achieve RA readings greater than without a transformer and with S1, S2 turned off, then the transformer can be considered serviceable.
When assembling, you need to know that R1 is two variable resistors assembled in one case and changing synchronously. Capacitors C1 and C2 are adjusted within small limits to obtain at pin 13 of the microcircuit the maximum sinusoidal and uniform signal at all frequencies. Instead of diodes VD1, VD6, you can use other high-frequency diodes. Instead of RA, you can use any arrow indicator of the recording level of a household audio tape recorder. Below is a list of elements on the basis of which this transformer control circuit is built: