I am working on an old desktop power supply unit. There are no PCB's and I thought the best way to start repairing it would be to build a wiring diagram. While working on it I found three transformer pairs tied together in a manner which I am unaccustomed.
I have attached our images of one of the pairs.
The large transformer is wired as you would expect. There are two winding, one with a 120vAC current, the other the output. (Given that I do not know how they are wired and if they even work I have not attached power to them yet as I would like to have an idea of how they operate before testing if possible.) The top transformer however has only one set out wires leading out of it and as best I can tell only a single winding. I could be wrong about the number of windings but I am reluctant to try tearing into it to find out in the event I can not get a replacement.
What I'm really hoping to find out is what principal these are operating on, with only two leads obvious the only other place for a secondary set of connections to the smaller transformer is under the (soldered?) legs. But the heat from the soldering would likely cause the insulation on a wire to melt and create a short with the housing and the case. The large transformer is bolted to the external housing which is metal and non-insulated. Therefore there is no way 120v could be presented here.
I have a few thoughts, some of which are strange. The first is that it is using an insulator which could withstand the heat that I am unaware of. (Most likely, but then why are the two units connected together instead of left apart and wired more conventionally?)
The second is that it could be the output of the large trasnformer is small enough that it is trasnfered to the small trasnformer through the casing, which is rendered safe by the case gound (This does not make sense to me but I may be missing something?)
The third is that the top element is not a transformer at all, but an induction coil used to vary the inducatance of the large transformer and change the output voltage by inducing a current controlled by a variable potentiometer on the unit. (I don't know enough to see that this would be possible or impossible, but it is an idea that someone with my amount of knowledge (Just enough to be dangerous) might try.)
The fourth, which just occured to me, is that it is some sort of method to trasnfer the indcutance of the coil and reverse it so that a steady DC output could be trasnfered from the AC Input of a transformer. This seems wildly impossible, but thinking about it I wanted to put it into words so I could look at the wiring on the outputs of both transformers and see if they meet back up anywhere to achieve something like this.
Or I could be missing something entirely, which is why I'm asking here before I try anything crazy.
I gave the part numbers and information on the part to a technician at Digikeys and she was not able to figure out what it is or if they had a replacement available. So until I get some idea of what they are I am hesistant to try putting too much time into repairing or diagramming a device that I may never get to function correctly because of these odd little things.
I have attached our images of one of the pairs.
The large transformer is wired as you would expect. There are two winding, one with a 120vAC current, the other the output. (Given that I do not know how they are wired and if they even work I have not attached power to them yet as I would like to have an idea of how they operate before testing if possible.) The top transformer however has only one set out wires leading out of it and as best I can tell only a single winding. I could be wrong about the number of windings but I am reluctant to try tearing into it to find out in the event I can not get a replacement.
What I'm really hoping to find out is what principal these are operating on, with only two leads obvious the only other place for a secondary set of connections to the smaller transformer is under the (soldered?) legs. But the heat from the soldering would likely cause the insulation on a wire to melt and create a short with the housing and the case. The large transformer is bolted to the external housing which is metal and non-insulated. Therefore there is no way 120v could be presented here.
I have a few thoughts, some of which are strange. The first is that it is using an insulator which could withstand the heat that I am unaware of. (Most likely, but then why are the two units connected together instead of left apart and wired more conventionally?)
The second is that it could be the output of the large trasnformer is small enough that it is trasnfered to the small trasnformer through the casing, which is rendered safe by the case gound (This does not make sense to me but I may be missing something?)
The third is that the top element is not a transformer at all, but an induction coil used to vary the inducatance of the large transformer and change the output voltage by inducing a current controlled by a variable potentiometer on the unit. (I don't know enough to see that this would be possible or impossible, but it is an idea that someone with my amount of knowledge (Just enough to be dangerous) might try.)
The fourth, which just occured to me, is that it is some sort of method to trasnfer the indcutance of the coil and reverse it so that a steady DC output could be trasnfered from the AC Input of a transformer. This seems wildly impossible, but thinking about it I wanted to put it into words so I could look at the wiring on the outputs of both transformers and see if they meet back up anywhere to achieve something like this.
Or I could be missing something entirely, which is why I'm asking here before I try anything crazy.
I gave the part numbers and information on the part to a technician at Digikeys and she was not able to figure out what it is or if they had a replacement available. So until I get some idea of what they are I am hesistant to try putting too much time into repairing or diagramming a device that I may never get to function correctly because of these odd little things.
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