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Old 11-04-2019, 05:53 PM   #1
EasyGoing1
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Default Re-purposing power supply parts

I would like to re-purpose the transformer from this 2013 MacBook Pro power supply, but I can't seem to locate the specific transformer they used in this power supply, and therefore I don't know how the terminals should be connected. I'm assuming that it converts AC down to 24 volts, but the last time I attempted to connect a salvaged transformer from which I could not locate its datasheet, I let the smoke out...

Here is a photo of the board. If the bottom image were slid upward it would overlay the top image and the pins of all components would match up. I also labeled the pins of the transformer so that when we discuss it, we can reference the pins accurately.



What I am trying to find out, is which pins can I connect to 120 so that I can measure the other side of the transformer and determine what the output voltage is?

Thank you for any input you can provide,
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Old 11-04-2019, 06:02 PM   #2
R_J
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Default Re: Re-purposing power supply parts

This is a high frequency switching transformer. It is not ment to be connected to 120vac. It likely operates at 20~100KHz
Pins 3&4 are likely the primary, 5&6 are feedback/run voltage and 1&2 are the secondary output
If you connect it to 120vac 60hz you will destroy it. Read about switch mode power supplies

Last edited by R_J; 11-04-2019 at 06:05 PM..
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Old 11-07-2019, 04:07 AM   #3
EasyGoing1
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Default Re: Re-purposing power supply parts

Quote:
Originally Posted by R_J View Post
This is a high frequency switching transformer. It is not ment to be connected to 120vac. It likely operates at 20~100KHz
Pins 3&4 are likely the primary, 5&6 are feedback/run voltage and 1&2 are the secondary output
If you connect it to 120vac 60hz you will destroy it. Read about switch mode power supplies
Good thing I created this post then.

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Old 11-07-2019, 04:21 PM   #4
PeteS in CA
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Default Re: Re-purposing power supply parts

The topology for that adapter is discontinuous flyback (the seeming lack of an output inductor is the big clue). That means that the main "transformer" is actually a coupled inductor. When switch Q1 is on, it charges the inductor. When Q1 is turned off, the energy stored in the inductor discharges into the output circuit. Those two devices on the output side you labelled "MOSFET" are probably rectifiers.

Not only is the "transformer" unsuitable for connection to 60Hz power, the core is gapped, probably with a spacer. That gap is what makes the part an inductor, and energy is stored in that gap. You probably can only use that "transformer" as a replacement part in a more or less identical circuit.
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