transformer primary wires - identification

[pheonix358]

Hi all,

I have a transformer taken from an aiwa P80 defunct amp. Secondary voltages are 60VCT and I think a 12V or so. The problem is that I have 4 primary wires. Black, Yellow, Orange and White. The amp had voltage selector for 110V 220V and 240V. I need the 240V setting. I tried once and blew the power board circuit breaker. Hmm, I need help please. Only thing I can think of is to put say 9 volts on the secondaries and measure the primaries but, is there another (safer) way to do this.

Terry

[pheonix358]

The primaries all have resistance from 1.6 Ohm to 10.4 Ohms. This implies to me that the primaries are all tapped. That does not make sense, I thought there would be two windings that go in either series or parrallel.

Terry

[pjp]

And how does 2 windings that go in either series or parallel give you a choice of 110, 220V and 240V ?

[pheonix358]

Originally Posted by pjp

And how does 2 windings that go in either series or parallel give you a choice of 110, 220V and 240V ?

I have no idea! It gives either 110 or 220 in series or parallel. Wouldn't the wire guage have something to do with it?

Terry

[pjp]

No, the wire gauge wouldn't affect the voltage.

If you have a choice of 4 voltages, and only 4 taps on the transformer, I would expect one 0-240V winding with 2 taps, one at 110V and the other at 220V.

If you blew the fuse, you either wired the secondary to the mains, or the 220-240 section to the mains. Which means you had 240 * (240 / 60) volts or 240 * ( 60 / 20 ) - i.e. you exposed yourself to 960 Volts or 720 Volts.

Either way, you could have killed yourself.

edit: corrected an error in the math.

[pheonix358]

Originally Posted by pjp

No, the wire gauge wouldn't affect the voltage.

If you have a choice of 4 voltages, and only 4 taps on the transformer, I would expect one 0-240V winding with 2 taps, one at 110V and the other at 220V.

If you blew the fuse, you either wired the secondary to the mains, or the 220-240 section to the mains. Which means you had 240 * (240 / 60) volts or 240 * ( 60 / 20 ) - i.e. you exposed yourself to 960 Volts or 720 Volts.

Either way, you could have killed yourself.

edit: corrected an error in the math.

Thanks for the reply.

I know which ones are the secondaries. They are terminated with plugs.

What I think I did was to connect the primaries wrong. I have since measured the resistance and I think sorted out which wire is which, well I am assuming that the two wrires with the most resistance should be at each end of the primary.

I also know that the wire size has no effect on the voltage, but does the primary side effect the current draw.

PS. The power board I use has a good circuit breaker etc.

Terry