I bought a flyback transformer recently, 5908-05008, CF68A. However, when I try searching online for this model, there seems to be no pin out diagram or any information at all. Most of the FBT I saw had either 10 pins or 13 pins while this flyback has 9 pins.
I understand that there is 2 potentiometer for tuning Focus and Screen but other than that, I have no idea how to test it for it's winding, turn ratio, inductance value and KVA.
I was wondering if there is anyway to test and find out which pins are for what purpose and how to check the parameters for this flyback. Thanks!
Best Answer
Identifying FBT leads is not easy but it is not impossible. What you need is a dc24V power supply and a 1K ohm resistor. Connect the resistor on the positive terminal of the power supply. Draw two test probes, one from the negative terminal of the power supply and another test probe (positive) from the resistor.
Connect the volts meter across the resistor. This setup is actually a high compliance ammeter capable of forward biasing high voltage rectifiers.
Firstly to identify the EHT secondary winding, link the negative test probe to the EHT suction cup and cycle the positive probe thru each pins of the FBT. When the positive probe finds the end of the EHT winding, current shall flow thus indicates voltage readings in the volt meter. At this moment probe polarity can be reversed to verify the integrity of the rectifier diode.
The other pins of the transformer can be identified similarly. The primary usually have the highest resistance and it may have other tappings as well. High resistance will cause lower current flow thus exhibit lower voltage readings across the resistor.
Resistance is the function of the wire length and wire diameter. It is merely used to understand how the connections are made. Once all connections are figured out and understood, another test can be performed to understand the turns ratio.
FBT operates at around 16KHz. A low voltage DC source such as 12V chopped at 16KHz can be injected in one of the isolated winding and voltage measurements can be taken across all windings identified in previous step. Some windings will produce higher voltages compared to another. Mark them accordingly and by now the turns ratios should be apparent.
During this step BEWARE of the high voltage at the EHT suction cup..!! It can easily go beyond few kilovolts.