how do i know if my flyback output is ac?

[TanTric]

i have a couple of flybacks, 2 from old color tvs (a big one, other small), and 5 from color monitors.

the big transformer i think it produces ac, but i cannot put it to work, maybe its allready dead/shorted? i tryed the FB primary and also a 4 turn primary that i wounded in the core and nothing!

have made the test to find the output -0V pin, and it showed me 6v if im not in error, with a 12v power source (just connected my DMM positive probe to flyback output and the negative probe to -12V source, then tryed the pins with the +12V source.)

its possible to remove the diode from a DC output flyback transformer, if so how do i make it without braking the core?

thank you all

BOOM

[gyula]

Hi,

Here are some links maybe of help:

testing flyback transformer-easiest test method

POWERLABS' High Voltage Solid State Flyback Driver

How to find the primary and the secundary coils of a FlyBack transformer by Jean-Louis Naudin

To remove diode(s) (there maybe more in series) all you can do is to cut up carefully the side of the plastic body with a dremel cutter or like cutter, not an easy task... there is a photo in the inside "world" of an opened trafo in the first link, but there can be different placements inside, there are many types...

Be careful if you include your trafos in an oscillator, start with low supply voltage, for even under 10V supply instead of 24-30V the High voltage output still has several kiloVolts, very dangerous!

Good luck, Gyula

Addition: Flyback transformer - HvWiki
Youtube video: YouTube - simple flyback transformer setup/usage
may also be useful for you.

If you find original part numbers on the trafos labels, you can have chance to identify their pins, there are cross reference possibilities on the web, like the Spanish Diemen company.

[seth]

Hi Juju

I found my pins by measuring 1 ohm on my multimetre between sets - then, when i found 2 pairs which both measured 1 ohm, 2 pins at one side, and 2 pins at the other, i assumed that one side was the primary coil and one side the feedback coil. (No power is necessary in any part of this test....just a multimetre)

My output pin also measured 1ohm with any of the 4 pins id already identified as the primary and feedback (AGAIN - NO POWER). It also had the handy letters ''OU'' (!!!!!!) written underneath it, which made me sure it was an output pin.

Hope this helps! Remember, keep swapping polarity, and swapping pins! trial and error will get you there!

[redeagle]

You can use a diode setting of a multimeter. Mine tells me what my voltage drop over the diode is with the leads swapped it shows no current.