Smoke coming from potentiometer? Uh oh. [Solved]

[shesaysidontlisten]

So I tried and failed at audio apparently.

I'm hoping someone can help me figure out where I went wrong...

I added the PWM lines to the config.txt. I then wired the new L and R out to the L and R in on my PAM8403.

20171110_184549-1328x747.jpg (245.63 KiB) Viewed 6203 times

20171110_184541-1328x747.jpg (252.88 KiB) Viewed 6203 times

I then wired the amp L and R +'s to the pot ins. Then I wired the L and R pot outs to the headphone left and right in.

20171110_184517-1328x747.jpg (209.02 KiB) Viewed 6203 times

20171110_184526-1328x747.jpg (325.89 KiB) Viewed 6203 times

20171110_184456-1328x747.jpg (231.55 KiB) Viewed 6203 times

I wired the pot ground to the headphone ground and headphone ground to the power strip ground. The PAM8403 is powered and grounded to the power strip as well.

I then proceeded to generate smoke from (almost positive) the potentiometer. I cut the audio from Pi to test that nothing was fried on the Pi. Lucked out there.

I used the pins from wermy's vid for the pot and the headphone diagram from Felder.

I didn't put my low pass filter together yet, but I can't imagine that would have helped. Did I mess up some pins somewhere?

Pardon my rats nest. It will all look about 30% more organized when I start putting it in the case.

Thanks all!

[rodocop]

Pretty sure you have the wrong gpio pins used. The yellow (pwm1) and blue (pwm0)wires are the pwm (see photo) Are you doing mono audio? If so you only need one of the pwm wires. It seems like your red wire is at ground, and that yellow wire is not on a pwm pin.

SpoilerShow

[shesaysidontlisten]

Pretty sure you have the wrong gpio pins used. The yellow (pwm1) and blue (pwm0)wires are the pwm (see photo) Are you doing mono audio? If so you only need one of the pwm wires. It seems like your red wire is at ground, and that yellow wire is not on a pwm pin.

SpoilerShow

I'm trying to do stereo. I used the 13th and 18th pin per the PWM audio guide. I found this and it looks like I should be using pins 33 for L and 12 for R. Right?

SpoilerShow

rpi_zero_io_pinouts.jpg (44.88 KiB) Viewed 6178 times

Do I have the pins on the pot right? It was hard to tell if ground was left when looking at the wheel head on or looking at the back of the wheel.

[rodocop]

That diagram is right. But your wiring does not match. Double check you gpio wiring.

SpoilerShow

[shesaysidontlisten]

That diagram is right. But your wiring does not match. Double check you gpio wiring.

SpoilerShow

Yes, I used the 13th and 18th pins, which it turns out are NOT GPIO13 and GPIO18.

And now I feel stupid. Wonder if the pot will still work after this. Soldering those tiny wires to the straight pins SUCKS.

[rodocop]

Yeah. You can try it. But if it was smoking....might be toast. Also for the pot when looking down at it. With the black wheel on top, use this diagram. Ground is the left pin

http://cdn.instructables.com/F6K/QVPA/G ... .LARGE.jpg

[shesaysidontlisten]

Yeah. You can try it. But if it was smoking....might be toast. Also for the pot when looking down at it. With the black wheel on top, use this diagram. Ground is the left pin

http://cdn.instructables.com/F6K/QVPA/G ... .LARGE.jpg

Moved over to the correct pins (and a new potentiometer) and all good now. Hooray! Thanks, rodocop!

So a few quick questions. Lots of pops and hissing, especially while changing the volume with the wheel. So I know the filter should help with this. Does that go before the amp?

Also, is USB audio considerably better, or is this just the perils of audio from an emulator?

Also, the volume can get insanely loud through the headphones. Is there a way to limit volume level coming out of the pi to make sure it doesn't accidentally deafen me?

Last question! I haven't connected the speaker yet, but at 0 volume via the wheel there is still slight audio. Similarly to the above question, is there a way to drop the minimum volume output level to ensure silence or near silence when the potentiometer is zeroed out? I guess I'll save this question until after I connect the speaker and see if that is silent with the wheel on zero.

[rodocop]

You can adjust the sound in emulation station too. On the retro pi menu there is volume adjust option I believe. As for the volume pot...they seem to cause some static and don't always work great. If it's bad enough you can get rid of the pot completely. And use volume controls via hotkeys. If you do add the filter i'd put it before the volume wheel and amp.

In regards to the headphones. I honestly have not input. Since I never use them. Even the builds I have done with headphones I haven't even tested them out haha.

Usb audio will always be better than pwm audio. So if you are not happy with the pwm could be worth trying usb audio.

[shesaysidontlisten]

You can adjust the sound in emulation station too. On the retro pi menu there is volume adjust option I believe. As for the volume pot...they seem to cause some static and don't always work great. If it's bad enough you can get rid of the pot completely. And use volume controls via hotkeys. If you do add the filter i'd put it before the volume wheel and amp.

I think I'll just reduce the volume down to where full wheel doesn't hurt but is plenty loud. That should hopefully lower the minimum volume enough to be muted when all the way down.

Usb audio will always be better than pwm audio. So if you are not happy with the pwm could be worth trying usb audio.

I am desperately trying to avoid using a USB hub. I already have a Teensy, so I'm capped out. :/