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I have torn down a crappy Antec Neo HE power supply that would turn on randomly only. It's rated 430W, amongst these 3.3V/22A, 5V/14A, 3 x 12V/16A.

I'm planning to use it for parts in a home made power supply project. There is an unidentified transformer (marked VRL35W015 on its top, SBI 4.2 E150436 C on its side) which I'd like to know how I can check its features, e.g. frequency range, max current, voltage and whatnot. The SBI 4.2 marker lead me to a Taiwanese company that does unfortunately not publish the specification for that transformer type.

Apparently the transformer has two primary and two secondary windings. How can I check the characteristics of this transformer? Is there a typical circuitry I can build to check it out?


EDIT: Actually the only code that is specific to this transformer is VRL35W015. SBI 4.2 and E150436 seem to be reference model or something similar. There is a small transformer next to this one, both share the same SBI 4.2 and E150436 but the smaller one has a different identifier: VEE19FRC9.

This transformer also has 6 pins on the secondary, wired together in adjacent pairs on the PCB, the primary four pins, independently connected. The document pointed to by Andy Aka seems to confirm, like the hinted thread, the fact that this transformer has been specifically designed for this Antec Neo HE. Not any reason to ditch this transformer, to me of course.

I will observe (frequency, voltages and apparent ratios) with my oscilloscope how the transformer behaves. This will hopefully give me basic information, which I'll further use in my "quest". Lot of fun ahead.

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  • \$\begingroup\$ Such transformers are custom build for a specific design. Although you could use it in your own design you would be designing around the transformer of which you know little ! You do not know for which frequency it is designed or what it's maximum currents are. Of course you know that this is a high frequency transformer, you cannot use it directly on mains voltage. \$\endgroup\$ – Bimpelrekkie Nov 17 '15 at 14:39
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    \$\begingroup\$ Indeed. My question hence is about knowing more about it before using it. Is it possible to determine its features experimentally? \$\endgroup\$ – user59864 Nov 17 '15 at 14:41
  • \$\begingroup\$ What kind of specialist equipment, for example? \$\endgroup\$ – user59864 Nov 17 '15 at 14:44
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    \$\begingroup\$ @Nasha: very well, see my answer. \$\endgroup\$ – Fizz Nov 17 '15 at 15:28
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Yes it's possible to extract the characteristics of an unknown flyback transformer. But as @FakeMoustache said, it can be an expensive proposition. Basically you need a network analyzer. Here is a tutorial on using one to determine the lumped-element characteristic of an "unknown" flyback xfmr. Note that they still assume known the turns ratio... and the model they get is still not quite matching the xfrm at very high frequencies.

You might also want to read chapter 21 of Transformers: Analysis, Design, and Measurement on ways to basically do all those measurements separately. There are a lot of parameters to determine.

enter image description here

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  • \$\begingroup\$ Thanks for this constructive response, too. I think in fact all 3 (two answers here plus the hinted thread) do respond to my question. I'm flagging your response as an answer for how elaborated you made it. \$\endgroup\$ – user59864 Nov 17 '15 at 20:00
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    \$\begingroup\$ @Nasha: and for SMPS flyback transformers in particular (which often have three windings), you'll also want to look at onsemi.com/pub_link/Collateral/AN1679-D.PDF from page 4 onwards. \$\endgroup\$ – Fizz Nov 17 '15 at 20:06
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There does appear to be a published UL document that contains all the build and test info for a transformer itemized as "E150436 C". This is just a snippet: -

enter image description here

The UL document can be found here and maybe this transformer has been used in a couple of products. It's towards the end of the document that you get the coil stack diagram, coil turns and pin-outs.

Just check to see that it looks the same before doing anything risky.

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  • \$\begingroup\$ Thanks for your response. FTR I searched using DuckDuckGo but could find nothing. I didn't try Google, should have. I'll see what I can do with that. Thanks a bunch for providing a response! \$\endgroup\$ – user59864 Nov 17 '15 at 15:00
  • \$\begingroup\$ And it even includes testing PCBs! Wish I could up your answer twice. \$\endgroup\$ – user59864 Nov 17 '15 at 15:10