I'm thinking there's something wrong with the TPA3116 input components/layout. A 10k pot shouldn't have had much effect on the volume level.
@doctormord:
Could you point me where exactly should I solder 1500-2000 uF cap ?
25V or 35V of the cap?
Could you point me where exactly should I solder 1500-2000 uF cap ?
25V or 35V of the cap?
Strange...when I posted this reply, it works after click on thumbnails.
full res-photo:
front: http://www.mikomp.org/pcb/front.jpg
back: http://www.mikomp.org/pcb/back.jpg
full res-photo:
front: http://www.mikomp.org/pcb/front.jpg
back: http://www.mikomp.org/pcb/back.jpg
Best possible fix is like attached. Remove red marked components, solder wires in place like shown.
Drawback:
No volume control via potentiometer anymore
No Aux/Line-in (Aux might still work if they used the ADC of the BT-module.)
Keep the wires close together (R+/R- and L+/L-)
Drawback:
No volume control via potentiometer anymore
No Aux/Line-in (Aux might still work if they used the ADC of the BT-module.)
Keep the wires close together (R+/R- and L+/L-)
Attachments
Hello, many thanks for possible solution ! I will test it this weekend.
One question:
From point where (R+/R- and L+/L-) is marked I go directly to speakers +/- terminals (skipping connecting speakers cables to blue terminals on this board)
From what I understand I'm leaving after this solution option with adding capacitors.
One question:
From point where (R+/R- and L+/L-) is marked I go directly to speakers +/- terminals (skipping connecting speakers cables to blue terminals on this board)
From what I understand I'm leaving after this solution option with adding capacitors.
To the output terminals as usual. The fix on the picture is to bypass the Linedriver between the bluetooth DAC output and TPA Input.
Your need to remove 4 resistors and 4 capacitors. Then solder 4 wires to the pads marked by the dots. Keep the wires together in pairs. R+/- and L+/-
Hi ! Mod successful ! The idle noise is much less audible !
doctormord you made my day ! Thank you !
doctormord you made my day ! Thank you !
Does the noise figure changed? Before i'd guess it was some kind of modulated digital noise, now it should be more like static noise. If there are still artifacts of digital noise left, we will need to alter the power supply for the BT module.
In both cases it was a static noise. Without mod the noise is way to high ! When music stops, only the noise comes from the speakers. For exemple when I turned on this device, and device is waiting for BT connection - only noise is present.
After the mod noise is still present - static, but value of this noise is much less - let's say on acceptable level for me. Of course in perfect scenario the noise could be gone 🙂
After the mod noise is still present - static, but value of this noise is much less - let's say on acceptable level for me. Of course in perfect scenario the noise could be gone 🙂
You may try lowering the gain of the TPA. If you can actually overdrive the amp with your BT source, then reducing gain is an option with good success.
Alright, then remove the resistor "753" near the TPA chip. This lowers the gain from 36dB down to 20dB.
(I might be neccessary to change the "433" resistor for a 10k ("103"), but remove "753" first and test)
(I might be neccessary to change the "433" resistor for a 10k ("103"), but remove "753" first and test)
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