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I have attached some pictures for your information and other details as follows:To get rid of the humming simply turn it off. If you want better suggestions give us more information.
Mike.
Separate the grounds as in a star and connect them together only at the main filter capacitor ground.
The input ground, the output ground and the amplifier ground should all connect together only at the negative wire of the main power supply filter capacitor then there is no voltage drop of hum along a path. It is called a "star" ground.I could not understand what you say. Please elaborate it. Thank you!
Thank you for your explanation !The input ground, the output ground and the amplifier ground should all connect together only at the negative wire of the main power supply filter capacitor then there is no voltage drop of hum along a path. It is called a "star" ground.
The input ground, the output ground and the amplifier ground should all connect together only at the negative wire of the main power supply filter capacitor then there is no voltage drop of hum along a path. It is called a "star" ground.
You probably have a wrong or missing connection in your messy tangle of wires.
Please post the wiring details of the Bluetooth receiver so that we can see the functions of its 6 wires. Your photo shows that its red wire does not connect to anything.
Is the output of the LA4440 amplifier set for stereo or for one bridged output? Is it muted?
I have never seen such poor soldering before. Don't you use 63% tin/37% lead name-brand rosin core solder?
Photos do not show functions of the wires that the missing schematics will show. Please post the schematics.
A schematic is very important for any electronic circuit. You can make it by copying the manufacturer's schematic of the Bluetooth receiver, the power supply and the datasheet of the LA4440 amplifier. Then you will see the missing wire.I don't have any schematic.
Then you will see the missing wire.
Never mind the "missing wire", first fix the awful soldering and short circuits on the board.
Look here:
View attachment 108133
JimB