I have a standard transformer with 7 wires:2 black2 red2 yellow1 red/yellow stripedWhat connections do these wires correspond to?That is, which should connect internally to the primary coil, the secondary coil, and coil-taps (based on the number of wires, I assume that the secondary coil is tapped).I must determine this in order to connect the wires (externally) appropriately.Any help is greatly appreciated!
Raptor gave good info. I would add just a few points: 1. The high voltage winding usually has the smaller gauge wire. 2. The high voltage (primary) winding also usually has a higher DC resistance and fundamental frequency impedance than the secondary. 3. Be sure to scrape the insulation off the wires before checking the resistance. Many years ago, an idiot I was working with didn't recognize that the wires had enamel insulation on them, and connected the transformer backwards. It was a 480 V / 1 V (or so) instrument transformer. We lost a lot of good equipment and nearly lost people because of that screwup. The recorder saw 2 kV before it died.
Pin Number Wire Color Function 1 Not Used Not Used 2 Black Ground 3 Grey Right Positive 4 Grey/Black Right Negative 5 Blue/White Amplifier Remote 6 Red 12 Volt Switched 7 Yellow 12 Volt Constant 8 White Left Positive 9 White/Black Left Negative
The odds are fairly good that the black wires are primary, the red wires are one secondary, the yellow wires are another, and the striped wire is a center-tap on one of the secondaries. There is a standard ritual for identifying the characteristics of an unknown transformer: first, use an ohmmeter to identify which wires to a single winding, and which winding has the highest resistance. Next, apply power; the safest way is to use a 40-watt (or thereabouts) light bulb in series with a 120 volt source, and connect this to the highest-resistance winding. Now measure the voltages across each winding. That will give you the turns ratios, and you can get an indication from the physical size of the device as to how much power it can handle.
