Hello all,
This is my first post in the forum, really enjoy and appreciate the information provided. I am a novice in electronics, just trying to have a little fun and learn something along the way. I hope I am posting this in the right area.
I purchased an inexpensive 5V 2X3W bluetooth audio board from ebay. Didn't come with any schematics/instructions (big surprise). One thing I noticed is that my board didn't match the pictures on the listing (again, big surprise), and from comparison, it appears there might be some components missing. I've done research on my own, but haven't found any details about these devices. It works, and sound quality is OK with the exception of a couple of items:
1) There is a voice that announces when it powers up and when bluetooth connectivity changes. The sound quality of the voice is louder and clearer than the audio from a connected bluetooth device.
2) With the bluetooth device connected, I hear a faint hum from speakers. Not enough to ruin sound, but noticeable.
I have attached a photo of the board I have (1st image), with yellow circles around the sites identified for 2 capacitors (C9 and C10) and 1 resistor (R4). When comparing to the board on the listing (2nd image), the resistor is a 100K, but I have no idea what the capacitors are, and have already found out I need to remove and test to determine, as these have no markings. Also, there appears to be an empty spot (L5) for an inductor, but I have yet to find a board that contains this component. The seller is trying to find a schematic for me, but I am not very hopeful.
All that being said I am trying to determine:
1) Are these missing components, or possibly a redesigned board that no longer needs those?
2) Are the sound issues I mentioned related to the missing components? If not, any thoughts/suggestions on correcting these?
3) If anyone has any additional info about this board, would you mind sharing?
Appreciate any and all help/input!
http://i1237.photobucket.com/albums/ff473/vanenk/DSCN14772_zpslgyoy43s.jpg
http://i1237.photobucket.com/albums/ff473/vanenk/w_zpsycc3mglk.jpg
![a>](https://www.diyaudio.com/forums/<a href="<a href=http://s1237.photobucket.com/user/vanenk/media/DSCN14772_zpsgfintqxz.jpg.html" target=_blank>http://s1237.photobucket.com/user/vanenk/media/DSCN14772_zpsgfintqxz.jpg.html"</a> target="_blank"><img src="<a href=http://i1237.photobucket.com/albums/ff473/vanenk/DSCN14772_zpsgfintqxz.jpg" target=_blank>http://i1237.photobucket.com/albums/ff473/vanenk/DSCN14772_zpsgfintqxz.jpg"</a> border="0" alt="5V 2X3W board-mine photo DSCN14772_zpsgfintqxz.jpg"/></a>)
![a>](https://www.diyaudio.com/forums/<a href="<a href=http://s1237.photobucket.com/user/vanenk/media/w_zpsjmjn6eqp.jpg.html" target=_blank>http://s1237.photobucket.com/user/vanenk/media/w_zpsjmjn6eqp.jpg.html"</a> target="_blank"><img src="<a href=http://i1237.photobucket.com/albums/ff473/vanenk/w_zpsjmjn6eqp.jpg" target=_blank>http://i1237.photobucket.com/albums/ff473/vanenk/w_zpsjmjn6eqp.jpg"</a> border="0" alt="5V 2X3W board- listing photo w_zpsjmjn6eqp.jpg"/></a>)
This is my first post in the forum, really enjoy and appreciate the information provided. I am a novice in electronics, just trying to have a little fun and learn something along the way. I hope I am posting this in the right area.
I purchased an inexpensive 5V 2X3W bluetooth audio board from ebay. Didn't come with any schematics/instructions (big surprise). One thing I noticed is that my board didn't match the pictures on the listing (again, big surprise), and from comparison, it appears there might be some components missing. I've done research on my own, but haven't found any details about these devices. It works, and sound quality is OK with the exception of a couple of items:
1) There is a voice that announces when it powers up and when bluetooth connectivity changes. The sound quality of the voice is louder and clearer than the audio from a connected bluetooth device.
2) With the bluetooth device connected, I hear a faint hum from speakers. Not enough to ruin sound, but noticeable.
I have attached a photo of the board I have (1st image), with yellow circles around the sites identified for 2 capacitors (C9 and C10) and 1 resistor (R4). When comparing to the board on the listing (2nd image), the resistor is a 100K, but I have no idea what the capacitors are, and have already found out I need to remove and test to determine, as these have no markings. Also, there appears to be an empty spot (L5) for an inductor, but I have yet to find a board that contains this component. The seller is trying to find a schematic for me, but I am not very hopeful.
All that being said I am trying to determine:
1) Are these missing components, or possibly a redesigned board that no longer needs those?
2) Are the sound issues I mentioned related to the missing components? If not, any thoughts/suggestions on correcting these?
3) If anyone has any additional info about this board, would you mind sharing?
Appreciate any and all help/input!
http://i1237.photobucket.com/albums/ff473/vanenk/DSCN14772_zpslgyoy43s.jpg
http://i1237.photobucket.com/albums/ff473/vanenk/w_zpsycc3mglk.jpg
Last edited:
I can't open your pix. If you mean this one 5V Micro USB 2x3W Bluetooth Audio Receiver Digital Amplifier Amp Board TE657 | eBay
Without schematic, we have no idea but if you trace the missing components, you may find the capacitors trim the Xtal frequency which on a cheap board is not needed but R4 (100k) is anyone's guess. Maybe gain setting?
Hum will be a power supply/earth loop issue.
Without schematic, we have no idea but if you trace the missing components, you may find the capacitors trim the Xtal frequency which on a cheap board is not needed but R4 (100k) is anyone's guess. Maybe gain setting?
Hum will be a power supply/earth loop issue.
Looks likes R4 might be to pull the shutdown pin high (active low). Similar boards use 100K there, but the PAM8403 datasheet says it has an internal pull-up so it can be left floating.
BTW, you need to use the "direct link" URLs from PhotoBucket...
BTW, you need to use the "direct link" URLs from PhotoBucket...
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.