| hongrn |
I need to rewire my LM4780 amp to eliminate a ground loop issue. I have an Avel Lindberg 330VA 25Vx25V that I need to configure to have a center tap, in other words, 25V-0-25V. Please take a look at this schematic and tell me how to wire this.
If I wired both primaries and secondaries in series, I'll end up with 230V for the primaries, and 50VAC for the secondaries. I only need 25VAC (rectified into 35VDC) for my amp. Do I use this wiring scheme and plug it in to get 25VAC, since we have 120VAC in the US? Or do I keep the primaries in parallel and wire the secondaries in series?
Thank you for your help.
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| motherone |
You have dual primaries so that you can put the primaries in series or parallel for 115/230VAC. The secondaries are the same way (25VAC @ double the current, or 25-0-25).
So, the answer to your question is to put the primaries in parallel and the secondaries in series. You should definitely read up on how transformers work, though, so you understand why you're doing this. |
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| hongrn |
I've been at the Decibel Dungeon many times, just want to make sure I wire it correctly before plugging in my amp.
Thank you motherone. |
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| rabstg |
| Use the top left picture for the primaries and the bottom right for the secondaries. The tie piont fo the series coils needs to go to the Pwr supply ground (not the same as chassis ground) and you will have to use a bridge rectifier or a descrete bridge.. You will not be able to use the descret diodes in BrianGT's pwr supply board with out jumpers or modification... |
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| motherone |
Do you mean top right for primaries, and bottom right for secondaries?
The top left picture is just to show the color codes in relation to how the transformer is wound. |
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| rabstg |
| quote: | Originally posted by motherone
Do you mean top right for primaries, and bottom right for secondaries?
The top left picture is just to show the color codes in relation to how the transformer is wound. |
YES... My bad... Top right actually shows them paralleled. |
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| hongrn |
I am wiring the primaries in parallel and the secondaries in series. Thanks everyone.
Hong |
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| rabstg |
Note that yours is a dual secondary and the secondaries are in parallel to seperate bridges.
NOT the same as a series connection with center tap to a common grnd. |
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| rabstg |
| quote: | Originally posted by hongrn
I need to rewire my LM4780 amp to eliminate a ground loop issue. I have an Avel Lindberg 330VA 25Vx25V that I need to configure to have a center tap, in other words, 25V-0-25V. |
Is the end application a BrianGT kit or a home brew design?
And going form dual secondary to center tap is generally not the way to troubleshoot ground loops.
May I please ask you to elaborate on the end application (bridge rectifier scheme) and the motivation for change( Ground loop?). |
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