Can someone with patience for beginners please help me with this?
I'm trying to build my first 300w A/B Class Mosfet Power Amp.
I'm getting confused with how to connect the transformer to the power module. It looks so simple but I want to get this right. The loose separate bridge rectifier in the pic is not needed I think as BR1 is at the bottom of the power module.
I just need help, in 99.9% layman terms please, in how to connect the transformer to the power module and the on/off switch
Here's a photo to help anyone who can give advice.
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.
Many thanks to anyone who has the patience!
DIY-AB-Class-Mosfet-Amp — ImgBB
I'm trying to build my first 300w A/B Class Mosfet Power Amp.
I'm getting confused with how to connect the transformer to the power module. It looks so simple but I want to get this right. The loose separate bridge rectifier in the pic is not needed I think as BR1 is at the bottom of the power module.
I just need help, in 99.9% layman terms please, in how to connect the transformer to the power module and the on/off switch
Here's a photo to help anyone who can give advice.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.
Many thanks to anyone who has the patience!
DIY-AB-Class-Mosfet-Amp — ImgBB
If - as your nom-de-plume suggests you are British and your casing is metal cutting off the earth at a mains voltage of approx =240V AC is not recommended .
JLH was forced to reinstate an earth in his 80W Mosfet design when it went on the market due to UK Regulations & Industrial Standards .
Of course for your own use you can do without the earth as it introduces mains derived noise/distortion just be aware if you electrocute yourself you can only blame-----yourself .
There are other ways used in audio hi-fi to "separate " ground earth and signal earth with a 10 ohm resistor.
JLH was forced to reinstate an earth in his 80W Mosfet design when it went on the market due to UK Regulations & Industrial Standards .
Of course for your own use you can do without the earth as it introduces mains derived noise/distortion just be aware if you electrocute yourself you can only blame-----yourself .
There are other ways used in audio hi-fi to "separate " ground earth and signal earth with a 10 ohm resistor.
Be careful and cut nothing and do not connect mains to the IEC socket yet.
1/ look at your transformer markings to understand the wire colours and report this back to us
2/ one pair of wires, possibly the Red/Black, will be the primary - these connect to AC mains after the fuse and On/Off switch. But confirm the colours on the transformer markings please.
3/ the other 3 pairs of wires will be the lower voltage secondary output. The markings on the transformer will label the colours and respective voltages.
4/ the power supply module lower edge has a 4 way and 2 way terminal strip with labels printed - tell us what the labels say. This will guide your connections.
5/ the black component with 2 white components either side needs to be explained - perhaps a closer photo showing their labels. The bridge rectifier will be need I suspect.
6/ did you get any wiring instructions with this kit? If yes share it with us.
1/ look at your transformer markings to understand the wire colours and report this back to us
2/ one pair of wires, possibly the Red/Black, will be the primary - these connect to AC mains after the fuse and On/Off switch. But confirm the colours on the transformer markings please.
3/ the other 3 pairs of wires will be the lower voltage secondary output. The markings on the transformer will label the colours and respective voltages.
4/ the power supply module lower edge has a 4 way and 2 way terminal strip with labels printed - tell us what the labels say. This will guide your connections.
5/ the black component with 2 white components either side needs to be explained - perhaps a closer photo showing their labels. The bridge rectifier will be need I suspect.
6/ did you get any wiring instructions with this kit? If yes share it with us.
Here is a closer photo, and thanks for all the help so far!
Power-Module — ImgBB
Power-Module — ImgBB
An externally hosted image should be here but it was not working when we last tested it.
It's an EBB 150-2, haven't found a model number, but for someone who can better understand it this schematic will help.
EBB-Power-Module-Schematic — ImgBB
Please read within the quote i am still getting to grips with multi quoting within a single post
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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...
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...
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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!
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?
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
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
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
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