Beginner Help with Wiring Toroidal in DIY Amp

[epicyclic]

Originally Posted by SquireTrelawney

The loose separate bridge rectifier in the pic is not needed I think as BR1 is at the bottom of the power module.

Correct


I presume the first step is to cut off the ground wire at the on/off switch end on that Belden mains cable I've put in there so I'm left with blue/brown on the cable, which is now earthed at the IEC socket end. This is UK wiring too.


Yes you have connected the safety earth directly to chassis at the IEC connector good . You could have more neatly used 2 wire from the IEC to the switch.


You have a dual primary voltage toroid both 115V and 230V capable and you obviously need to use it at 230V so blue and brown are used as the 230V input as normal but you now need to connect grey and violet together, solder them to one another only and properly insulate with shrink wrap etc. PS use 2 layers of insulation .


Now the secondary side connect orange to AC1 , yellow to AC2, black to AC3 and red to AC4.

Please read within the quote i am still getting to grips with multi quoting within a single post

[Mark Tillotson]

The main inputs are designed for a centre-tapped secondary or dual secondary (the latter is probably what you have).

E2 and E3 are ground/centre, E1 and E4 are the two phases.

If you have two secondaries you need to determine their phasing. One wire of each secondary goes to ground, the other to E1 or E4. If you get the phasing wrong the rectification will be half-bridge rather than full-bridge, and the AC voltage between E1 and E4 will be zero volts. This is incorrect, but not catastrophic.

If you get the phasing right the rectification will be more efficient and the AC volage between E1 and E4 will be twice the voltage of each secondary.

If you accidentally connect both ends of one of the secondaries to E2 & E3 you'll have shorted that secondary - AVOID this at all costs. A multimeter in resistance mode will allow you to identify each secondary (and the primary come to that as primary resistance is much higher than secondary).


For any wound component it costs nothing to check the winding connectivity with a multimeter - even if the pinout is given, why not
double-check and avoid any chance of shorting a winding? You also discover if the things got a dud winding doing this...

[SquireTrelawney]

Originally Posted by epicyclic

Please read within the quote i am still getting to grips with multi quoting within a single post

Thanks for that, that was the advice I needed, concise and easy to grasp for a complete beginner! I will get back to work and report back. Thanks for the help!

[SquireTrelawney]

I'd like to thank everyone who replied offering help, but especially epicyclic for his easy to follow advice. It works beautifully and is a great encouragement in the hobby/passion when something goes right! The amp is nice and silent, no hum, and sounds very smooth. The only thing that needs attention in the future is if I turn it off with the source still playing, the speakers still continue to play the music for a while, does anyone have any advice on what's causing this? Or how to fix the issue?

[duncan2]

The electrical storage in the power supply capacitors is allowing the music to slowly die down.


In other words the drain imposed on the power supply is not enough to instantly cause a voltage drop stopping any output .


You could of course impose an artificial heavier load but a more elegant way is to fit Bleed resistors across each large value power supply capacitor .


As you like things simply put read-


Bleeder Resistor: What is it, and Why is it Used? | Electrical4U

[epicyclic]

Originally Posted by SquireTrelawney

The only thing that needs attention in the future is if I turn it off with the source still playing, the speakers still continue to play the music for a while, does anyone have any advice on what's causing this? Or how to fix the issue?

This is normal and is as Duncan says , it also shows your power supply caps are in good shape . If you really wanted to get rid of it you could add a speaker protection circuit board but then you would have the issue of powering it .

Glad the amplifier is up and running