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Daedalus · 09 July 2021, 09:39

The issue is most likely the power supply you're using with the PicoPSU. Some PicoPSU models require a direct 12V input, others allow a range like 12-24V. If yours specifically requires 12V, then it doesn't do anything with that rail at all - it simply passes it directly to the Amiga, which then uses it directly for the audio circuitry. Many cheap power bricks are very noisy, and that noise is being passed directly into the Amiga's audio circuitry, resulting in the distortion you hear.

Do you have a multimeter? It might also be worth checking that the 12V rail is what it should be - you can measure it at the floppy power connector. The -12V rail should be generated by the PicoPSU, it's worth checking that that's ok too, though you'll probably need to check that at the PSU itself.

I've observed both video and audio noise with different power bricks feeding various PicoPSU models, including what should be decent Dell laptop chargers. The PicoPSU's advantage is its size, but that comes at a cost of filtering, so it really needs a very clean input supply to work well.

09 July 2021, 09:39	#2
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,369	The issue is most likely the power supply you're using with the PicoPSU. Some PicoPSU models require a direct 12V input, others allow a range like 12-24V. If yours specifically requires 12V, then it doesn't do anything with that rail at all - it simply passes it directly to the Amiga, which then uses it directly for the audio circuitry. Many cheap power bricks are very noisy, and that noise is being passed directly into the Amiga's audio circuitry, resulting in the distortion you hear. Do you have a multimeter? It might also be worth checking that the 12V rail is what it should be - you can measure it at the floppy power connector. The -12V rail should be generated by the PicoPSU, it's worth checking that that's ok too, though you'll probably need to check that at the PSU itself. I've observed both video and audio noise with different power bricks feeding various PicoPSU models, including what should be decent Dell laptop chargers. The PicoPSU's advantage is its size, but that comes at a cost of filtering, so it really needs a very clean input supply to work well.