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Transformer with two primaries
Transformer with two primaries
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Old 6th May 2021, 12:26 PM   #1
alephotos is offline alephotos  Italy
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Default Transformer with two primaries

Hi, I removed this transformer from a non-working amplifier. To make the primary work at 230V I connected YEL with BLK, I isolated WHT and I used BLU and BRN to connect it to the 230V mains voltage. it's correct? The secondary is only a 24V. Thank you
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Old 6th May 2021, 12:37 PM   #2
Mooly is offline Mooly  United Kingdom
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Transformer with two primaries
It sounds correct in what you have done although I'm not sure why there are two 0V tags for the left hand winding. Could there be a thermal fuse between those two?
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Old 6th May 2021, 12:37 PM   #3
Vovk Z is offline Vovk Z  Ukraine
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I don't know what is '0V-0V-115V' but in any case you have to connect it to mains only through a some large ballast safety resistance (and a small fuse of cause). It may be large 1k resistor, or 40-60W incandescent lamp. And measure a current (or a voltage across a safety resistor) - if it is small then everything is fine.

I'm not sure about 'Blue' - it may potentially be a screen wire or something else.

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Old 6th May 2021, 02:13 PM   #4
Marra is offline Marra  United Kingdom
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Transformer with two primaries
Check for continuity with your DMM before connecting to power.
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Old 7th May 2021, 07:10 PM   #5
alephotos is offline alephotos  Italy
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It seems to work fine, I connected a resistor of about 27 ohm (old resistor for water heater) as a load, the voltage remains constant and the transformer does not heat and makes no noise. Would it be better to use WHT and isolate BLU?
Thanks
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Old 7th May 2021, 07:29 PM   #6
russc is offline russc  England
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Quote:
Originally Posted by Mooly View Post
It sounds correct in what you have done although I'm not sure why there are two 0V tags for the left hand winding. Could there be a thermal fuse between those two?
The wiggly line could be a representation of a fuse symbol.
Then you would join white & black for parallel 115V operation but connect mains to blue to protect both windings.
For 230V, as the op stated in post 1 for fuse protection.
Googling transformers, the more usual arrangement is to fuse both primary windings so only 2 wires per primary.
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Old 7th May 2021, 08:18 PM   #7
nigelwright7557 is offline nigelwright7557  United Kingdom
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0 0 115 is unusual.
Quite often its 0-110-115 to adjust for mains voltage variation.
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Old 10th May 2021, 06:01 AM   #8
Diabolical Artificer is offline Diabolical Artificer  United Kingdom
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Does the amp schematic shed any light on the 0v~0v - 115v winding?

Andy.
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Old 11th May 2021, 05:35 AM   #9
alephotos is offline alephotos  Italy
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unfortunately I don't remember the amp model
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Old 11th May 2021, 07:31 AM   #10
alephotos is offline alephotos  Italy
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I tried the following links and got these values
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