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Question on 3.7W Class D Audio Amp - No Sound
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Question on 3.7W Class D Audio Amp - No Sound

by lucgallant on Tue Apr 22, 2014 11:56 pm

Hi there,

I purchased a 3.7W Class D Audio Amp for a project.

https://www.adafruit.com/product/987

I've soldered it up per the instructions and hooked it up to a 1/4 size perma-proto board. I've tied in 5V from the 2A adapter.

I hooked up two, 8Ohm, 1W speakers, one to each L/R channel.

I'm supplying the amp from a Raspberry Pi audio output jack. I know the sound works well coming out of there because my headphones and small Bose speaker play it very nicely when connected directly.

For some reason, the amp is not outputting anything (I've got it hooked up to the two simple speakers). I measured the current going into the chip, it's about 4 mA. Seems close enough to the 2.6 mA stated by the datasheet (Quiescent Supply?), especially given that I'm measuring using a meter that only measures in Amps, not mA.

http://www.adafruit.com/datasheets/MAX98306.pdf

Any ideas? I'll take some good pictures tomorrow but if there is anything right off the bat, that would be appreciated. The power supply current does not vary when I try to play a sound, either. I also did not wire anything to the Shutdown pin.

Any tips would be appreciated. Thanks.
lucgallant
 
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Re: Question on 3.7W Class D Audio Amp - No Sound

by adafruit_support_mike on Wed Apr 23, 2014 3:01 am

Try wiring the shutdown pin HIGH. If that's floating, it can assume any value.

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Re: Question on 3.7W Class D Audio Amp - No Sound

by lucgallant on Wed Apr 23, 2014 10:24 pm

So I took a few photos. Here they are.


IMG_1570 (Large).JPG
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IMG_1570 (Large).JPG (168.83 KiB) Viewed 731 times
IMG_1569 (Large).JPG
2
IMG_1569 (Large).JPG (170.35 KiB) Viewed 731 times
IMG_1568 (Large).JPG
3
IMG_1568 (Large).JPG (180.07 KiB) Viewed 731 times


I measured current in whether the Shutdown pin is set to 5 V or Gnd - no difference, 0.004 A. Setting the pin to 5 V does not help the sound issue either.

I had this wired up to a Perma-proto but moved to the breadboard once I started getting no sound.

I checked continuity from the audio plug into the RasPi all the way to the amp pins themselves, all good. Power's good, I checked the pins on the chip itself...

Not sure what more I can do to troubleshoot it? The chip does say "AEV BAD +" on it, I notice the website one also says that, not sure if that means anything or not.

Anyway, any input would be appreciated. Thanks.
lucgallant
 
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Re: Question on 3.7W Class D Audio Amp - No Sound

by adafruit_support_mike on Thu Apr 24, 2014 6:12 pm

I don't see anything likely to be a problem in your connections or soldering, so let's try a new amp.

Send a note to support@adafruit.com with a link to this thread and the folks there will get you a replacement.

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Re: Question on 3.7W Class D Audio Amp - No Sound

by krazylego56 on Sun Apr 27, 2014 1:43 am

Hi I seem to be having the same problem. I just got mine and a day after I got it, it seemed to just stop working, power is going to the board but if I plug my speaker into the board it doesn't work. There is nothing wrong with my speaker or audio jack because I can get the two to work just fine without the board any ideas on what I could do?

A beginner to electronics.
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Re: Question on 3.7W Class D Audio Amp - No Sound

by adafruit_support_bill on Sun Apr 27, 2014 6:06 am

@krazylego56 - Post some photos showing your soldering and connections to the board. What speakers are you trying to drive with it?

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Re: Question on 3.7W Class D Audio Amp - No Sound

by krazylego56 on Sun Apr 27, 2014 11:15 am

Here are the pics....
Image
I am using a bone conduction speaker.
Image

Image
I have wired it up similar to the project adafruit posted for the bone conduction speaker minus the switch and battery pack onto the breadboard to see if it works before doing anything else.
The day I got the board it worked fine and then about an hour later it just stopped working.
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Re: Question on 3.7W Class D Audio Amp - No Sound

by adafruit_support_bill on Mon Apr 28, 2014 5:43 am

That all looks right. If you contact support@adafruit.com with a link to this thread we can send you a replacement.

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Re: Question on 3.7W Class D Audio Amp - No Sound

by lucgallant on Fri May 02, 2014 12:52 pm

Hi there,

I received the new amp today, soldered it up, works great. Thanks for the help.

Finished product (pre-amp fix), shown here:

http://c-3po-talker-project.blogspot.ca/

Luc
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