Author Topic: Screen Is Displaying Only White  (Read 2584 times)

Randall (Admin)

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Re: Screen Is Displaying Only White
« Reply #15 on: March 04, 2022, 05:30:41 PM »
Those messages are fairly standard.  I would expect to see a line about creating a port for capture_1.  You might look for that by running journalctl with just "-u jack".

You might check to make sure your audio isn't being misrouted.  Load up the pedalboard named "Default" which has in1 connected to out1 and in2 connected to out2.  Add a wire from in1 to out2 and in2 to out1.  See if audio passes then.  If so but not with the original Default, then you probably swapped your R & L wires on input or output.

If still no input being heard, it's probably time to debug the input buffer side of things.

https://www.treefallsound.com/wiki/doku.php?id=troubleshooting_guide#no_processed_audio

I might start by testing the voltage across the U3 shown by the yellow dots.  If that reads around 3v, then proceed to signal trace.



markb

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Re: Screen Is Displaying Only White
« Reply #16 on: March 09, 2022, 10:25:31 AM »
I was able to get the audio to work, but now there is a hum and a lot of noise.

Randall (Admin)

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Re: Screen Is Displaying Only White
« Reply #17 on: March 09, 2022, 02:47:33 PM »
Hum and noise are often improved once mounted in an enclosure.  Abnormal amounts of hum is typically a grounding issue.  If you have any other pieces of gear in the signal chain, it might be good to eliminate those to rule out possibility of a ground loop.

Does the noise exist for all pedalboards?  Even "Default" and lower gain chains like AmpBud?  Some high gain effects and amps are noisy just like the physical gear they emulate.  That noise is generally of the "white noise" variety - fairly constant and usually across the frequency spectrum.  If what you're hearing though is regardless of the effects, and sounds "digital" - random-ish pops and quick squeaks and squeals, that would probably be burst noise sneaking in from the raspberry pi.  The pi is simply noisy and that noise can be inductively coupled into the audio lines or via the shared ground.  Try physically moving the jumper wires connecting the audio card to see if that makes a difference.

Possible also that the supply power is just not very clean.  There is a spot on the board for adding an additional filter capacitor (C5).  You could add most any electrolytic cap with a voltage rating over 10v and value of 10uF or more to see if that cleans it up.  You wouldn't even need to solder it in, just make certain of it's polarity and make sure the leads don't short to each other or anything around them.

     

markb

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Re: Screen Is Displaying Only White
« Reply #18 on: March 09, 2022, 03:16:10 PM »
It does happen with all the pedal boards. I will try the suggestions that you recommend. Could it possibly be a bad volume pot? I remember seeing something similar on your Github page under the closed issues.

https://github.com/TreeFallSound/pi-stomp/issues/8

Randall (Admin)

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Re: Screen Is Displaying Only White
« Reply #19 on: March 09, 2022, 04:10:36 PM »
Ok.  Does the noise appear roughly equal for both channel 1 and 2?

I generally wouldn't expect the volume pot, but maybe worth checking.  The output of the audiocard simply goes thru the volume pot, to the relay then the output jack, so you could test the resistance of that path from audio card to jack is less than 10ohms or so (when the volume is cranked).  Same for ground, just a few ohms.  If not, check your wiring.