Re: Some Toroid Transfoprmer Questions!!!!
Lee,
Here is what I do in this case. It looks like two bundles of wires coming out of each toroid. Bundle 1 looks like (black, red, green) and (yellow, orange, gray). Bundle 2 looks like (brown, black, white) and (purple, blue, white). I think one of the bundles is the primary and one of the bundles is the secondary, every toroid I have seen is made this way.
Based on the number of wires in each group (3) it seems you have center tapped (CT) windings. Of course, the primary CTs were probably connected to power ground and the secondary CTs were probably connected to the chassis to prevent shock in the case of an internal transformer short.
You might be able to assume that green and grey are the CTs on one side of the transformer and the white wires are the CT on the other side of the transformer. In any case you can run some resistance tests to confirm that the primary wires are not physically connected to the secondary wires. Then you can isolate the two windings in each side of the transformer because each CT coil is independent of the other (disconnect the bridge rectifier).
Once you have confirmed the three wires going to each CT winding, you can run voltage tests. This transformer has a close ratio of turns because the primary windings are each 120V and the outputs are 163V and 112V. Or more properly 81.5V + 81.5V and 56V + 56V on the two secondaries. Of course you want to find the lowest voltage because that will identify the smallest winding on the output side. If you connect the secondaries to 120V AC power you would get higher outputs because you are using the transformer as a step up instead of a step down.
Once you get the voltages identified by the proper CT windings you need to identify the phase. You can do that on the dual trace oscilloscope. Just make sure you have the "coupling" set to AC and the "trigger" set to the 'scope channel you are using for the primary AC winding, not the internal AC of the 'scope. Use a low voltage like 10V AC and check the waveform on the other primary. Then connect the primary in-phase windings together in parallel (120V and 120V) and look for the same phase on the secondaries and mark both of the in-phase outputs as the 'positive' outputs. You can then hook up 120V on the paralleled primaries and check the voltage on the outputs. You should have 81.5V - 0V - 81.5V and 56V - 0V - 56V.
Of course, you will want to eventually connect the outputs in series to give you the 163V and 112V to power up your bad ass amplifier. You could just terminate the 112V winding and have all the wattage go to the 163V winding. Because you have two toroids, that would give you +163V and -163V or close to +/- 200V after rectification and filtering. Geez, a 400V swing PS, watch out!
