How To Locate The Primary Winding Of Flyback Transformer

By on November 24, 2008



flyback schematic

Got a question from ERG member:

Can the Blue Ring Tester that I purchased from you be able to test the TV Flyback Transformers?

Jestine- Yes you can

And what If I do not have some of the TV schematic diagrams, how should I identify which pins in pair. Meaning to say pin No.?  & pin No.? are related for testing.

Jestine- Check for the flyback pin that goes to the collector pin of HOT and the B+ pin (supply from power supply). That is the primary winding of flyback transformer.


If you are repairing the CRT Monitor then you have to find out from center pin of the B+ FET that goes through a Diode  (ultra fast recovery diode) and then to the flyback pin. Another pin was from the collector of HOT. Both the pins is the primary winding of the flyback transformer. Try practice to find these two pins because i came across quite a number of technicians could not trace these pins. The primary winding is important if you are in the CRT TV/Monitor repair because a shorted/ partial shorted winding could cause the equipment to shutdown, low power, power blink or even blow up the HOT. If you come across a shorted HOT please make sure you test this primary winding before you put in a new HOT otherwise if the primary winding have problem, it may takes a split of seconds to kill the new HOT.

Again, it come back to the important of using flyback tester/Blue Ring Tester to find out the bad winding. Without the tester, surely it would take you a longer time to troubleshoot the problem that related to shorted primary winding in Flyback transformer.

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11 Comments

  1. russ

    February 22, 2011 at 5:09 am

    If I don't have a schematic how do I know where the B plus is? Are there some more clues you can give? Are they ever at the same pin number, or do they ever read a particular ohm? Can you show me some exambles on a flyback and on a schematic?
    Thank you
    Russ

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  2. admin

    February 22, 2011 at 8:44 am

    HI Russ,

    For a TV, just trace the 110 vdc line of the power supply and it will lead you to the B+ pin of flyback.

    Jestine

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  3. lito mendoza

    September 28, 2011 at 8:42 am

    jestine,

    aside from the 2 pins of the primary winding in the lopt/fbt transformers, what are the functions of the remaining pins? just in case the primary winding of lopt/fbt is ok, will the remaining pins of the transformers be the cause of the tv/monitor shutting down?

    thanks a lot,

    lito

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  4. admin

    September 29, 2011 at 8:39 am

    Hi Lito,

    Try this link:

    http://electronicrepairguide.com/flyback-transformer-pinout.html.

    usually the secaondary winding will not cause shutdown unless it is shorted.

    Jestine

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  5. worku

    October 17, 2011 at 9:32 am

    how to check the fly back ,it is normal or not normal

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  6. admin

    October 18, 2011 at 3:25 am

    HI Worku,

    Try this link:

    http://www.electronicrepairguide.com/testing-flyback-transformer.html

    Jestine

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  7. jojogreg

    September 5, 2012 at 11:11 pm

    hi jestine,
    Can i measure the primary winding of the flyback transformer using analog or digital multimeter?How can i know that the primary winding is defective?Is it shorted or a zero resistance?What is the right range setting in   the analog meter if possible..

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    • Jestine Yong

      September 6, 2012 at 3:47 am

      Hi JOJO,

      You can't use analog/digital meter to check on the primary winding because a shorted winding the meter will still show good reading (Ohms value). You need Blue Ring Tester to locate shorted winding in flyback transformer.

      Jestine

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  8. boy ukel

    November 15, 2013 at 7:46 am

    halo mr jestine...i got a crt tv that have a red led like standby..when i check the 100uf 160v on secondary has blown...i replace it and the cap become hot and looks like gonna explode again...so i check all the sorrounding component..but nothing shorted...check the HOT....also good...check all the component around flyback..also no luck finding bad component....can mr jestine help me??

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    • Jestine Yong

      November 15, 2013 at 10:37 am

      Hi Boy,

      Try check the 100uf 160 volt cap again before it blow to see how many volt across it.

      Jestine

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  9. Denis Luleti

    December 17, 2013 at 3:22 pm

    Thanks a lot i finally located the primary windings of a flyback it has always been a headache for me but thanks to Jestine's recommedations i easily got it.

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