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Old 31st August 2011, 08:34 PM   #1
CST10 is offline CST10  United States
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Default How to measure transformer output

Erm, can't find a good place to start. This was pulled from a junked Soundesign am/fm/tuner/phono unit. Need to figure out how to measure the different voltages that this transformer can provide..

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Don't know which of the output wires to test, or in what combo..

Last edited by CST10; 31st August 2011 at 08:53 PM.
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Old 1st September 2011, 08:08 AM   #2
Mooly is offline Mooly  United Kingdom
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The red and black will be mains in.

When testing an "unknown" its good practice to use a bulb in series with the primary to limit current if you made a mistake.

So you have 6 wires on the secondary. The green and blue look thicker then the others. These probably supplied the output stage etc

I would guess that these are a ?-0-? In other words a split centre tapped winding with blue as zero. So power it up and measure on AC volts between the blue and each green in turn.

The orange black and yellow ? Switch off and see if there is any electrical connection between these and the three just tested. Use meter on ohms. I'm guessing not.

So now power up again and measure AC volts between all combinations of these three wires and write them down. It should then hopefully make sense as too what it is.
Installing and using LTspice IV. From beginner to advanced.
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Old 1st September 2011, 10:15 AM   #3
AndrewT is offline AndrewT  Scotland
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Originally Posted by Mooly View Post
When testing an "unknown" its good practice to use a bulb in series with the primary to limit current if you made a mistake.
very definitely good advice.

I suggest you never direct power a mains project from the mains until after everything has been tested and proved to be correctly wired.
regards Andrew T.
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Old 4th September 2011, 07:32 AM   #4
CST10 is offline CST10  United States
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Thanks for the advice guys. Sadly, won't be able to use it on my current project, but it's got a nice ~24v on the green wires, ~12v with them individually, and the 5.5v and ~4v on the lesser wires.

Finally, an easy and straight answer on how to measure these..
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