ZZ9000AX digital ground noises issue

  • Amiga model: AA3000+
  • 680x0 CPU: cyberstorm Mk3 060
  • RAM Configuration: 16 onboard + 128 on Mk3 + 256 (ZZ9000)
  • Kickstart, AmigaOS Versions: 3.1.4/OS3.9
  • ZZ9000 Firmware version: 1.13
  • ZZ9000 Driver version: 1.13
  • Monitor model: HP (lazy to go look exactly :D)
  • Other Zorro cards: X-Surf100, Deneb, Prelude replica

Very recent happy owner of ZZ9000 + AX, i’d like to know if others users face ground noises issue or if it’s my own configuration.
By ground noises, i mean all bus activity. hard drive, mouse pointer, and constant background noises.
Very likely ground loop or badly separated analogue/digital ground on the pcb itself.

Am i alone in this case?

As i mentionned, i also have a prelude replica, without any issue.

Not seen in our testing so far. Perhaps an EMI issue? What’s your audio listening/test setup?

setup is very simple, i use a little usb “sound bar” powered from mains with a usb charger, so not directly powered by the amiga. which could have explain the possible ground loop.

i’ll try without the paula passtrhough, then maybe try the original commodore daughterboard, i forgot to mention the firebird daughterboard in the setup description, maybe a ground loop exist with it.

i’ll test this soon and let you know.
thanks :slight_smile:

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tests done, and it’s effectively related to paula passthrough.
in fact the passthrough doesn’t work at all, can’t get anything from paula.
noises totally disappeared when unplugged.

i double checked and everything was correctly connected.
i also tried with the original A3000 daughterboard, and nothing better.
seems something is wrong with my AX?

edit : i’ll also check my motherboard… not impossible i did something wrong i didn’t saw when i assembled it.

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damn, it seems that my AA3000+ pcb might be the problem.
according to the original A3000 schematics, audio go from U402 pin 8 and 14 to pin 73 and 75 of CN451.

on my AA3000+ which use more or less the same silkscreen from the A3000 for the audio part, i found nothing connected to CN621, no wonder why it doesn’t work…
i’ll ask hese more informations, but i guess this explain a lot.

edit : i added bodge wires, and sure, less noises and more sound…
don’t know why it wasn’t routed, but it wasn’t.
i got a bit of distortions, i don’t know if picking directly on op-amp output is the best place, but according to both A3/4000 schematics (if i understand correctly) it’s where it’s supposed to be.

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please can you confirm me which signals you’ve used for the passthrough?
did you used filtered audio, or raw audio, or both?

i’ve talked with hese, and he told me than daughterboard pin 73 and 75 are related to superDMAC signals on the AA3000. and also than extension passing paula used filtered audio instead of raw.
but the fact is the passthrough didn’t worked before i put bodge wire to pin 73 and 75 of daughterboard.

i get a bit confused with all of that :smiley:

You can flip around the AAUD connector on ZZ9000 to switch between raw and filtered pins IIRC. (GND is in the middle)