Hello, I am tearing my hair out trying to figure out the wiring on this LM3886 power supply. I think that AC1 and AC2 are each a pair (0v 18v) secondaries and that the lower board connection is 18v and the one above 0v on the left of the board and the same on the right but they are not marked and I don't know how to test the MUR860. I have been going round in circles and started relatively confidently but now am completely confused. I assembled the boards 12+ years ago so would like to finish them 🙂 Any help will be hugely appreciated.
Attachments
You use a transformer with two 18V secondaries.
One secondary pair goes to AC1 and AC1, the second secondary goes to AC2 and AC2.
The white line at the diodes represents the "back" metal tab of the TO-220 diode - that second photo is correct.
On the output side, you can either tie the two grounds together (PG+ and PG-) to make a dual rail supply (-24Vdc ..0Vgnd...+24V) or you can keep both separate. In some cases, the two were joined at the amplifier board, in some you tied them together are the power supply board.
One secondary pair goes to AC1 and AC1, the second secondary goes to AC2 and AC2.
The white line at the diodes represents the "back" metal tab of the TO-220 diode - that second photo is correct.
On the output side, you can either tie the two grounds together (PG+ and PG-) to make a dual rail supply (-24Vdc ..0Vgnd...+24V) or you can keep both separate. In some cases, the two were joined at the amplifier board, in some you tied them together are the power supply board.
Post both sides of the board here.
AC1/AC1 is one secondary.
AC2/AC2 is the other.
AC1/AC1 and AC2/AC2 are independent windings, and are isolated from each other.
If you print out the schematic and trace it out while looking at the board, you should be able to understand it.
Be really careful about installing the diodes. There's only one right way.
Large capacitors also.
AC1/AC1 is one secondary.
AC2/AC2 is the other.
AC1/AC1 and AC2/AC2 are independent windings, and are isolated from each other.
If you print out the schematic and trace it out while looking at the board, you should be able to understand it.
Be really careful about installing the diodes. There's only one right way.
Large capacitors also.
Yes, that is right. The fault is in the lack of clear instructions.
Make certain that the two AC1 wires have mutual continuity before soldering.
Same for the pair of AC2 wires.
Twist the two wires of each pair together to reduce noise.
I worry more about the proper diode polarity installation.
The implication is that the white lines represent the metal tab on the back of the diode.
But the proper board marking is a diode symbol, with arrow head at anode, and arrow tail at cathode.
Make certain that the two AC1 wires have mutual continuity before soldering.
Same for the pair of AC2 wires.
Twist the two wires of each pair together to reduce noise.
I worry more about the proper diode polarity installation.
The implication is that the white lines represent the metal tab on the back of the diode.
But the proper board marking is a diode symbol, with arrow head at anode, and arrow tail at cathode.
Thank you 🙂
Here is a photo of the flip side of the board
Thank you for replying. Here is a picture of the other side of the board. The one thing t
Thank you replying. One thing that I am still not sure about is wiring the secondaries to the board. I think that I should connect 18v to the lower solder connection and 0v on the top one (like the picture below). Is that correct?
Here is a photo of the flip side of the board
Attachments
Thank you to everyone who answered my questions 🙂
I have it up and running now after a bit of experimenting with a bulb tester and it is testing as expected. That's the final piece of a puzzle that I began 14 years or so ago before children and adulting made me put it in a drawer.
I have it up and running now after a bit of experimenting with a bulb tester and it is testing as expected. That's the final piece of a puzzle that I began 14 years or so ago before children and adulting made me put it in a drawer.
A single secondary winding like AC1/AC1 has two leads, and they are interchangeable.
This is because it is AC voltage, and there is no polarity.
If it were DC voltage, you would have to distinguish between the two wires of the winding,
but transformers only work on AC voltage.
This is because it is AC voltage, and there is no polarity.
If it were DC voltage, you would have to distinguish between the two wires of the winding,
but transformers only work on AC voltage.