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Old 23rd October 2013, 03:19 PM   #1
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Default Toroid secondary colors help

Hi everybody, Im new to this forum, but have been lurking for a while. Im building a LM3886 chip amp and have this toroid I got out of a Durabrand receiver; it has secondary wire color combinations that I have never seen before: 2 blue, 2 white, and 1 orange. Can someone please shed some light on how to wire these?
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Old 6th November 2013, 03:43 PM   #2
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Can anyone please shed some light on this for me. I tried uploading a pic, but for some reason the site will not let me.
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Old 6th November 2013, 04:59 PM   #3
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Do you have a multimeter to measure resistance between all those wires?
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Old 6th November 2013, 05:14 PM   #4
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It's nearly impossible to answer your question. Standard transformer wire colors are not followed by a large number of manufacturers. As sextaafondo suggests, use your multimeter and measure the resistance. This will allow you to 'pair' the wires and identify the secondary windings.
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Old 7th November 2013, 09:31 AM   #5
AndrewT is offline AndrewT  Scotland
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Insert each transformer lead out into it's own separate receptacle of an insulated terminal strip.
Build a mains bulb tester.

Connect the assumed primary wires to a mains plug top.
Insert the transformer plug top into your bulb tester output socket.
Switch ON.
Is the bulb LIT or DIM or OFF?

Report back.
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Old 7th November 2013, 08:47 PM   #6
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Quote:
Originally Posted by Frank Berry View Post
It's nearly impossible to answer your question. Standard transformer wire colors are not followed by a large number of manufacturers. As sextaafondo suggests, use your multimeter and measure the resistance. This will allow you to 'pair' the wires and identify the secondary windings.
OK so matching pairs should have continuity between them correct?
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Old 7th November 2013, 09:18 PM   #7
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Well, I am pretty sure I had it hooked up wrong because I blew the fuse that I had attached to the mains side.
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Old 8th November 2013, 03:57 AM   #8
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OK, here is what I got: the two blue I got 32 volts, between the orange one the blue, I get 16 volts, and between the two white, I get 9.6 volts. The white wires have no continuity to any of the other wires besides themselves. The big question is will this work for my chip amp that needs 28-0-28 volts?
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Old 8th November 2013, 07:02 AM   #9
AndrewT is offline AndrewT  Scotland
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What was your input voltage?
That input voltage will change slightly when you remove the bulb tester.
The input voltage will also vary as the supplier's mains voltage varies throughout the hour/day/month/year.

The 16Vac you measured is the open circuit voltage.
The loaded voltage is likely to be 4% to 15% below that.
Maybe 15Vac loaded.
You need a 230:22+22Vac running on a 220Vac supply to get +-28Vdc
If running on 240Vac, a 230:20+20Vac will get close to +-28Vdc.

Are the two white wires connected?
Quote:
The white wires have no continuity to any of the other wires besides themselves
Do the two whites wires develop a voltage across them when powered up?
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Old 11th November 2013, 09:08 PM   #10
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My input voltage is 110v . The white wires are around 9v. Could I wire a white and blue in series to get my voltage?
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