Music Module output signal is DC offset

Archive
41

I think both jasdev and Dave tried that with no effect. Can you confirm?

42

@ njbuch - No, I have not tried to add that circuitry to the GHI board. Iā€™m trying a controller board from a different manufacturer that has the VS1053b built-in, and has the line-out circuitry on-board. I ordered that board, and received it, but there were some problems, so I had to order a replacement. I should receive the replacement this week.

The other board is not NETMF, and requires a whole other development/debug toolset to get started, so is expensive initially. It is the one mentioned in my earlier post:

https://www.ghielectronics.com/community/forum/topic?id=13497&page=2#msg140652

Iā€™ll let you know how it works out.

43

Alright, I am going to give this hardware-stuff a try, I have laid out the following plan, please help me and see if it makes sense.

I dont want to hurt my music module too much, and I stared at the schematics, and realized that I might be able to pull it of with some extra circuitry on the outside of the jack for headset, if I just left the GBUF hanging without connection.

The plan uses three drawings, which I have attached.

The first is the original circuitry recommended by VLSI.
The second is the same drawing with anything not related to lineout removed.
The last is my helpless attemt to sketch the added circuitry.

List of components for breadboard:
R38 470ohm
R39 470 ohm
R40 100Kohm
R41 100Kohm
C1 3,3nF
C2 3,3nF
C24 10uF polarized
C25 10uF polarized

Thanks in advance for any assistanceā€¦

44

@ njbuch - Looks promising, but how will you connect the external circuitry to the board ground?

45

@ jasdev - I was planning to hook everything up one the same supply, tell me asap if you dont think I will succeedā€¦ :open_mouth:

46

@ njbuch - I think you will get sound out, but I donā€™t know if this will eliminate the noise. It depends on where the noise is coming from. This is tricky stuff, and Iā€™m certainly no expert. Dave McLaughlin may have a better idea about this than me.

47

Iā€™m a bit busy with a couple of work projects but I will hook up the circuit tonight and probe it with a scope and see where the noise is coming from.

48

@ Dave McLaughlin - Did you find the source?

49

I know the nights are long in South East Asiaā€¦ :wink:

50

pingā€¦I am still really eager to get a noise-free solution to play sounds with Gadgeteer in speakers.