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Pwm audio
Posted: Wed Jan 23, 2019 8:30 am
by Robochris
Guys, I’m at a loss.
So I swapped controller pcbs in one of my gbz. The audio worked for a few minutes and when I started messing with the volume control it went out completely. I have replaced every component in the audio circuit - speaker, amp, vol. wheel, and even swapped the pi itself. Flashed an new retropie install and added the pwm lines to the config.txt.
Checked continuity between all points and 5v at the amp.
Still no audio. At all.
Any ideas?
Re: Pwm audio
Posted: Wed Jan 23, 2019 9:54 am
by correia5022
Whats the board you are using?
Any photo of the wiring?
Re: Pwm audio
Posted: Wed Jan 23, 2019 10:27 am
by Robochris
- DBC2E8F9-C58D-448E-92D3-B21FFC6B18CE.jpeg (2.64 MiB) Viewed 6234 times
Glitchd gaming common ground.
Re: Pwm audio
Posted: Wed Jan 23, 2019 11:36 am
by rodocop
I would wire the PWM pins direct to the amp, and see if the speaker works. Then start adding components back in. The PWM pads on the PCB will go through the volume wheel before going to the amp, so confirm that it is working too. I also see that you have both PWM pins going to the common ground board, so why not use all 5 wires to the volume wheel? You would only use three for mono audio. The way you have it wired you will not be controlling any volume on the PWM R side.
Also, since you have both L and R connected to the amp, Bridge L+ out and R+ out and then connect that to the speaker along with a ground. (mix two channels to one for the speaker)
Also, to confirm, did you add the mono audio or stereo audio line to the config.txt, and be certain you have the proper GPIO pins connected to the pi.
Re: Pwm audio
Posted: Wed Jan 23, 2019 11:52 am
by Robochris
rodocop wrote: ↑Wed Jan 23, 2019 11:36 am
I would wire the PWM pins direct to the amp, and see if the speaker works. Then start adding components back in. The PWM pads on the PCB will go through the volume wheel before going to the amp, so confirm that it is working too. I also see that you have both PWM pins going to the common ground board, so why not use all 5 wires to the volume wheel? You would only use three for mono audio. The way you have it wired you will not be controlling any volume on the PWM R side.
Also, since you have both L and R connected to the amp, Bridge L+ out and R+ out and then connect that to the speaker along with a ground. (mix two channels to one for the speaker)
Also, to confirm, did you add the mono audio or stereo audio line to the config.txt, and be certain you have the proper GPIO pins connected to the pi.
I originally had all 5 wires hooked up and both channels to the speaker. this is just where I am at shuffling things around to get anthing out of the speaker.
I have used both mono and stereo lines to config.txt. (not at the same time.)
Re: Pwm audio
Posted: Wed Jan 23, 2019 11:59 am
by Robochris
rodocop wrote: ↑Wed Jan 23, 2019 11:36 am
I would wire the PWM pins direct to the amp, and see if the speaker works. Then start adding components back in. The PWM pads on the PCB will go through the volume wheel before going to the amp, so confirm that it is working too. I also see that you have both PWM pins going to the common ground board, so why not use all 5 wires to the volume wheel? You would only use three for mono audio. The way you have it wired you will not be controlling any volume on the PWM R side.
Also, since you have both L and R connected to the amp, Bridge L+ out and R+ out and then connect that to the speaker along with a ground. (mix two channels to one for the speaker)
Also, to confirm, did you add the mono audio or stereo audio line to the config.txt, and be certain you have the proper GPIO pins connected to the pi.
Ok, I ran the gpio pins to the amp. no sound. it seems the pi isnt out putting sound.
I also tried reassigning pins but that didnt work either.
Re: Pwm audio
Posted: Wed Jan 23, 2019 12:14 pm
by Robochris
okay. so i just hooked everything back up how it should be and I have sound. when i bridge the channels, I lose sound again.
Thoughts why?
Re: Pwm audio
Posted: Wed Jan 23, 2019 1:53 pm
by rodocop
Robochris wrote: ↑Wed Jan 23, 2019 12:14 pm
okay. so i just hooked everything back up how it should be and I have sound. when i bridge the channels, I lose sound again.
Thoughts why?
hmm, weird, if you loose sound when bridged, it might just be best to run mono audio instead. Then you don't have to worry about to. For the majority of older games mono is 100% fine.
Re: Pwm audio
Posted: Wed Jan 23, 2019 1:57 pm
by Robochris
rodocop wrote: ↑Wed Jan 23, 2019 1:53 pm
Robochris wrote: ↑Wed Jan 23, 2019 12:14 pm
okay. so i just hooked everything back up how it should be and I have sound. when i bridge the channels, I lose sound again.
Thoughts why?
hmm, weird, if you loose sound when bridged, it might just be best to run mono audio instead. Then you don't have to worry about to. For the majority of older games mono is 100% fine.
Yeah im fine with mono anyways. Now, again I lost all sound. I dont know what I want to do with it now.
Re: Pwm audio
Posted: Wed Jan 23, 2019 2:55 pm
by correia5022
(thats a aio board, not a common ground)
You bridge outputs? from the amp?
I dont think pam8403 amp likes bridged outputs.. i even think it would probablt fry it after some time..