View attachment IMG20220918115726.jpg




I found this unused amplifier board made of 3 TDA2030, but i can not understand the audio input. From the left you can see usb output, speaker output, Volume control. So where is the stereo input?

I am suspecting that this might be a mono board with subwoofer (top right), treble and midrange outputs.

How can i connect stereo aux and volume control at the same time.

 

Plug the USB Connector into your Laptop and hope You don't need a special Driver.

If You can get a Model-Number and the manufacturer's name
You might be able to download Drivers that will work, but it's very questionable.
It's possible, that if You tell Windows what type of device it is,
Windows may offer-up a Generic-Driver that might work.

Do You have an appropriate Power-Supply ?,
if not this project could wind-up being a huge waste of time and effort.
.
.
.

 

Plug the USB Connector into your Laptop and hope You don't need a special Driver.

If You can get a Model-Number and the manufacturer's name
You might be able to download Drivers that will work, but it's very questionable.
It's possible, that if You tell Windows what type of device it is,
Windows may offer-up a Generic-Driver that might work.

Do You have an appropriate Power-Supply ?,
if not this project could wind-up being a huge waste of time and effort.
.
.
.

I am going to use a step down transformer 12-0-12 of 2amp, and diode bridge rectifier. But my question was, how can i connect my phone to it using 3.5mm stereo jack and play music.


This is what i found from manufacturer

 

Plug the USB Connector into your Laptop and hope

NO.
That connector supplies +5V to a USB device. There is a ua7805 next to it. Do not get your computer involved in this.

 

NO.
That connector supplies +5V to a USB device. There is a ua7805 next to it. Do not get your computer involved in this.

Then? In the picture shown by the manufacturer, can i connect right channel left channel and ground input audio to the VC port? Its clearly written 2.1 then how can i input stereo signal to it. I'm confused

 

Maybe the amplifier looks like this. Just to be certain ohm meter from pin 4 to the speaker outputs. (do both channels)

The sub speaker amp is something like this. Then there is an op-amp filter before this.

Please check the wiring for the input. I think the two 15k resistors connect like the red lines I drew. There is a chance that the connector is Right, Ground, Left and the resistors sum L&R to get mono.

 

Hello,

It could well be that the subwoofer channel is derived from the stereo input.
Here is a page that shows an example:
http://worldtechnical.blogspot.com/2012/01/circuit-power-audio-amplifier-with.html#.YycUDWcWquU

Bertus

 

Maybe the amplifier looks like this. Just to be certain ohm meter from pin 4 to the speaker outputs. (do both channels)
View attachment 276483
The sub speaker amp is something like this. Then there is an op-amp filter before this.
View attachment 276485
Please check the wiring for the input. I think the two 15k resistors connect like the red lines I drew. There is a chance that the connector is Right, Ground, Left and the resistors sum L&R to get mono.
View attachment 276486

Actually this is how it really look like

 

Hello,

It could be that the VC connection is the input.
The middle pins of the potentiometers (output) should be connected to the VC input.

Bertus

 

Actually this is how it really look like

It looks like pin1 and 3 go to the two 15k resistors then add together. So this is likely L + R.

 

Hello,

It could be that the VC connection is the input.
The middle pins of the potentiometers (output) should be connected to the VC input.

Bertus

It looks like pin1 and 3 go to the two 15k resistors then add together. So this is likely L + R.

Okay then i will first take a stereo 3.5 jack and connect it with the VC connection in this order Lch,gnd,Rch (may need to interchange for a bit) without any potentiometer and let's see what happens.

 

It looks like pin1 and 3 go to the two 15k resistors then add together. So this is likely L + R.

Got one another question, i can already see a diode bridge rectifier, so can i attach a step down 3amp 12-0-12 to it(ac)?

 

I do not know the exact schematic but, of the 7 diodes 4 are a bridge rectifier. Input 12-0-12 and output of about -15 & +15.
Then there might be more diodes for the power supply for the op-amp. Only a guess, but it looks like it runs from an AC transformer.

Look at the 3 pin connector. Pin 1 should go to two diodes like D4,D4 and Pin 3 will go to two diodes like D2,D3. I added the CT connection. There might be two large capacitors in series connected on the outputs.

 

I do not know the exact schematic but, of the 7 diodes 4 are a bridge rectifier. Input 12-0-12 and output of about -15 & +15.
Then there might be more diodes for the power supply for the op-amp. Only a guess, but it looks like it runs from an AC transformer.
View attachment 276490
Look at the 3 pin connector. Pin 1 should go to two diodes like D4,D4 and Pin 3 will go to two diodes like D2,D3. I added the CT connection. There might be two large capacitors in series connected on the outputs.
View attachment 276491

Done testing. L,gnd,R input signal connected to the VC and both output channels are working fine, balance is fine. But, low humming present when I'm not playing any music and it goes away as soon as i touch the heatsink. Why is that?

Used 12-0-12 step down 3amp AC and no problems at all. Heatsink heating up really fast gonna need a exaust.

 

Hello,

Do you have a capacitor at each input channel?
It could be that DC on the input is giving problems.

Bertus

 

Hello,

Do you have a capacitor at each input channel?
It could be that DC on the input is giving problems.

Bertus

yes they do have 102uf caps. Should i Remove it? But they are connected to the treble output

 

no