Flyback Transformer Pin Identification

Discussion in 'General Electronics Chat' started by Richard Trump, Feb 28, 2016.

  1. Richard Trump

    Thread Starter New Member

    Jan 17, 2016
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    I know this is an old topic, but I've tried many of the old ideas with no luck. This is a 10 pin transformer from an old Magnavox color tv and I'm wondering if there is something wrong with it because my readings seem odd.

    First, I tried to find the 0V pin on the secondary by running 15V DC through the HV red wire and checking each pin for voltage. I found 0.54V on pins 2,3,5,6,& 9. A quick continuity check showed continuity between all of these pins and each other. This confused me at the start, because I expected to only find 1 pin for the 0V on the secondary so I don't know what to make of this. I tried reversing the polarity of the DC source and got no voltage that way so the polarity seemed correct.

    Secondly, I looked for the primary by measuring the resistance between all of the various pin combinations and found 12 combinations with resistance between 0.8-1.3 ohm. I had read that the primary pins are usually adjacent, the only ones meeting that criteria were pins 5-6 which had 0.7 ohm (but both of those seemed to be associated with the secondary circuit...possibly). Several other combos had resistances around .5 or less.

    Since I didn't know what to make of all this I thought I would try the brute force approach. I have an 11 volt AC source, so I ran that through every possible combination of pins that had shown resistance or continuity, and checked for any output from the red HV wire with each unoccupied pin as a possible 0V pin. From this I got about 16 combinations that produced an AC output, but none that were over 2 volts. This also confused me because I had expected a significantly higher voltage from at least one of these.

    This is the first flyback transformer I've tried to salvage, so I'm either missing something glaringly obvious to everyone, or I got a very strange/bad one here. The transformer itself is from Mexico, I googled all the numbers on it and found some documents in Spanish but they weren't very useful (I don't even know if they were about anything electronic). It also has a thick white wire coming from the top attached to focus/screen controls and a thinner white wire coming from the base ending in a single connector.

    Any suggestions appreciated. I just have my multimeter, 11V AC, and 0-15V DC sources for testing purposes.

    Richard
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Pictures of it would help, also what model tv was it from?

    Also Lopt are tuned to 15.6Khz, and dont work well at low frequencies like 50/60hz.
     
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  3. Richard Trump

    Thread Starter New Member

    Jan 17, 2016
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    It's a 19" Magnvox from 1992, Model given is RR1937 W122
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Ok, what are you trying to achieve, repair the tv or use the transformer for another purpose?
     
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  5. Richard Trump

    Thread Starter New Member

    Jan 17, 2016
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    I'm just salvaging this for hobby HV purposes. AFAIK the tv was functional, just not wanted, but I never plugged it in to check.
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Ok, well to test the transformer you need to find the primary winding, and pulse it at 15khz with around 100v dc, but i assume thats the question you're asking, whats the pinout....
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    Its not that simple - to start with, its 5th harmonic tuned, secondly the horizontal scan yoke forms a significant part of the inductance in that tuned circuit.

    That's why many TVs have an interlock link on the deflection plug.
     
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