I have a large transformer and I just can't figure out its pinout.

I simply want to make a high voltage circuit but can't find the proper coils.

One side has 2 wires whose resistance is 0.8 ohms and the other side has 13 wires. Some of those have resistances of about 0.4 ohms. I don't think that is normal. What am I doing wrong?

I am planning to plug this into a ZVS circuit and see if I can make some arcs.

My transformer: TKP0278-E142Z

Here is my transformer on eBay: https://www.ebay.com/itm/SONY-STR-DE997-Replacement-Repair-KGCOMP-Power-Supply-1-443-265-11-TKP0278-E142Z-/113208976789

  • 1
    \$\begingroup\$ What persuaded you to buy it from ebay and what is it about the technicalities that makes you think it's suitable for your arcing needs? Simpler: why did you buy it? \$\endgroup\$
    – Andy aka
    Commented Nov 11, 2020 at 17:58
  • \$\begingroup\$ I don't think he bought it from Ebay (though that's conjecture). I think he has one scrap, and that's the only weblink he could find that describes anything about it. \$\endgroup\$
    – Kyle B
    Commented Nov 11, 2020 at 18:02
  • \$\begingroup\$ use a 9 V block battery ... very, very briefly touch to one of the windings ... feel the output of the other windings with your hand \$\endgroup\$
    – jsotola
    Commented Nov 11, 2020 at 21:36
  • \$\begingroup\$ You can plug DC into a coil though. It will spark at the battery right. Also, the eBay link is just for more info, I found it from an old device. \$\endgroup\$ Commented Nov 11, 2020 at 22:14

2 Answers 2


Very low resistance measurements are "normal" for transformers. All you're measuring is the DC resistance of a long piece of copper wire. You're not measuring "anything" about the transformer itself.

Specifically, resistance won't tell you the turns ratio (which is what you need to know to boost or cut output voltage). You need to use an AC source and measure (preferably with an oscilloscope) the output. This is nowhere near as easy or as straightforward as you're hoping. You might consider just buying a properly spec'd transformer where you "know" what's inside. They're not really all that expensive.


*edit, see you just added a link to the same transformer on EBAY. That's an audio amplifier transformer. It may very well not have any high-voltage outputs (unless maybe one pair of wires is intended for a vacuum fluorescent display). I don't know anything about that Sony receiver, maybe you can find a schematic and it'll give you some clues....

  • \$\begingroup\$ Is there a way to do this still using a multimeter? I am using the Craftsman 82141 multimeter? I would like to use this transformer. If not, can you do this with a ATX power supply transformer? \$\endgroup\$ Commented Nov 11, 2020 at 17:34
  • \$\begingroup\$ Are you using this transformer to make the high voltage, or are you using it to power a ZVS module of some sort???? \$\endgroup\$
    – Kyle B
    Commented Nov 11, 2020 at 17:37
  • \$\begingroup\$ If you're REALLY CAREFUL, and you TAPE OFF ALL EXPOSED WIRES, you can use the voltage setting of your meter. Use the standard 120VAC coming from your house outlet on the input "primary" wires (assuming you know which ones they are), and then measure the voltages you're getting on each set of secondary wires. You can also use the resistance measure on the (unpowered) transformer to map-out what the coils look like inside - that will be tedious and probably error prone since you've not done this before. Really the best bet, find the schematic for that sony receiver and go from there. \$\endgroup\$
    – Kyle B
    Commented Nov 11, 2020 at 17:39
  • \$\begingroup\$ I think that is a bit too dangerous. Though if I find out the resistance of all the coils, how can I know where to feed it power and where the high voltage will be? Can you tell from the resistances? \$\endgroup\$ Commented Nov 11, 2020 at 17:54
  • \$\begingroup\$ That's just it my man - Measuring resistances won't tell you any of that. All it tells you is the resistance of the wire on that given coil. Transformers are AC devices - A resistance measure is a DC signal. You need to know how many turns on each coil (and the ratio coil-to-coil). You didn't say yet what your actual intent is. Are you powering a pre-built ZVS module? Or trying to build the whole circuit from scratch????? \$\endgroup\$
    – Kyle B
    Commented Nov 11, 2020 at 17:57

Here's the power supply portion of the schematic of the Sony-STR-DE997.

The transformer in question is T901.

enter image description here

It gives a fair idea of the voltages to expect on the secondary windings.

After application of 120 V ~ to the primary winding, measurement of the voltages across the secondary windings would give an indication of the primary voltage being 120 V ~ or 230 V ~.


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