flyback transformer

[dane8]

I have a flyback transformer from one of the small 12v portable black and white tv. Is there anyway to determine the primary and secondary pins without an external power supply. I also need to know the simplest way in discharging the HV in the crt. Is there a capacitor within the transformer and does this transformer store high voltage?

 

[Sceadwian]

A multimeter on conductance testing will show you what leads are electricall common and what their resistance is, you should be able to come to a rough approximation of the priamry/secondary and turns ratio if you know the wire thickness.

 

[smanches]

The main high voltage you have to discharge is the tube itself. Grounding clip with resistor attached to a screwdriver. Just touch the tip of the screw driver to the long end of the flyback where it connects to the tube.

 

[mneary]

There isn't usually a capacitor inside the flyback assembly. The "capacitor" in the circuit is constructed using the tube's glass envelope as the dielectric. The inside surface is the anode of the tube and is the + side of the capacitor. Some of the tube's outside surface is coated with a conductor and is the - side.

 

[dane8]

need help

Since it is from a 12v portable black and white tv, what input voltage would be needed to drive the flyback and what do u think would be the output from the hv? The input voltage to the primary pins is it DC or AC? I also need simple ways of determining the primary and secondary pins of the transformer.

 

[smanches]

The input to any transformer is AC.

I've seen TV flyback outputs from 10k to 100k volts. I'd guess around 10-20k or so for a small TV like that.

Measuring the resistance of the leads to each other should give you a pretty good idea of what's primary and what's secondary. The secondary will be a long wire with very thick insulation on it, since it has to handle the very high voltage.