Audio (or lack of) Issue with PMG4 MDD

Discussion in 'PowerPC Macs' started by Totalbearface, May 6, 2019.

  1. Totalbearface macrumors member

    Totalbearface

    Joined:
    Apr 19, 2019
    Location:
    United Kingdom
    #1
    Hi guys,

    Picked up a second MDD recently to add to my collection, and because it has the dual 1.42 processor so a nice lot quicker than my single 1.0 MDD. But I digress.

    It doesn't seem to output any audio at all. No start up chime from the internal (or external) speaker(s), when it boots into the OS it doesn't play any sounds either, no matter if the output is set to internal, external, etc. It recognises when something is plugged into the front and rear audio jacks, as well as the smaller 2.5mm jack for the Apple speakers (audio output changes accordingly depending on what's plugged in), and when nothing is plugged in externally it'll default itself to the internal speaker, but sound won't play out of any of them.

    This is with both a clean install of Tiger and Leopard. Under Leopard, it always shows the sound icon in the menu bar, but under tiger it disappears when nothing is plugged into any of the external jacks.

    Tried the usual PRAM reset using the keyboard shortcut and setting defaults / resetting NVRAM under open firmware, before and after clean OS X installs but still nothing. One thing I have noticed is occasionally when powering on the machine, instead of chiming it's as if the internal speaker gets power for a split second (no chime but kinda emits a noise like a speaker does when electricity goes to it), but other than that, nothing.

    Any ideas what it could be?
     
  2. eyoungren macrumors Core

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    ten-zero-eleven-zero-zero by zero-two
    #2
    Blown speaker?
     
  3. Totalbearface thread starter macrumors member

    Totalbearface

    Joined:
    Apr 19, 2019
    Location:
    United Kingdom
    #3
    Doesn't output sound to anything out of any output though; speakers or headphones via the front jack, rear jack and doesn't output anything to my apple pro speakers via the 2.5mm socket either. Recognises something is plugged in to them all, but outputs to none of them.
     
  4. RhianB macrumors 6502a

    RhianB

    Joined:
    Sep 3, 2016
    Location:
    505 USA
    #4
    Swap the dual 1.42 daughter card & hearsink into the fully working unit.
     
  5. Totalbearface thread starter macrumors member

    Totalbearface

    Joined:
    Apr 19, 2019
    Location:
    United Kingdom
    #5
    I did, it just runs at 1.13GHz.
     
  6. Raging Dufus macrumors regular

    Raging Dufus

    Joined:
    Aug 2, 2018
    Location:
    Kansas USA
    #6
    Hi Totalbearface, a few observations:
    1. The issue is almost certainly sound-related (I know, duh, but keep reading) as opposed to power-related. The noise from your internal speaker indicating it's getting power, is as it should be... and it's recognizing things plugged into the audio jacks, so they're getting power too. The flow of electricity causes the machine to register something there. All of this means power is probably not the issue.
    2. One caveat though: I can't explain why your sound icon would disappear/reappear from the menu bar in Tiger. That's strange behavior that I personally have never seen before. But I think it must be related to a system setting, which for some reason Leopard handles differently from Tiger.
    3. Speaking of system settings, have you checked your Audio/MIDI Setup? On a fresh install, there's no reason anything should be amiss there, but you never know. Given point #1 above, the issue seems to be with the quality, volume, or some other aspect of the audio that your Mac is putting out, since the result is the same across all types of audio output.
    Try this: Go to Macintosh HD>Applications>Utilities>Audio MIDI Setup. Under the "Audio Devices" tab you'll see properties you can change for the Audio Output, such as:
    • Format: this should always be "44100.0 Hz" for your built-in speaker (may be different for other outputs like external speakers). There's a drop-down menu, but at least for the built-in there shouldn't be any other options listed. If for some reason there are options (sometimes an application will make changes) then make sure it's set to 44100.0 Hz.
    • Below that you'll see some sliders for volume and an option for "Mute". Make sure that your sliders are moved over toward the right, and that nothing is checked under "Mute".
    See if that makes any difference. If not, I've got nothing.​
     
  7. Totalbearface thread starter macrumors member

    Totalbearface

    Joined:
    Apr 19, 2019
    Location:
    United Kingdom
    #7
    Thank you for the advice, will give that a shot as soon as I can get back to he machine and post an update on wether or not that brings any success!
     
  8. LightBulbFun macrumors 68000

    LightBulbFun

    Joined:
    Nov 17, 2013
    Location:
    London UK
    #8
    sadly it sounds like the audio chip on this MDD is dead

    however on your 1.13Ghz MDD, im guessing your using an Ex single 1Ghz MDD or Dual 867Mhz MDD?

    if so theres a resistor your supposed to remove from the logic board to enable the Motherboard to run at full 166Mhz bus speed and as such run your CPUs at full speed :)

    which you can read about here :) https://thehouseofmoth.com/ppc-overclocking-station/
     
  9. RhianB, May 8, 2019
    Last edited: May 8, 2019

    RhianB macrumors 6502a

    RhianB

    Joined:
    Sep 3, 2016
    Location:
    505 USA
    #9
    If that is the case, I wonder if an external audio card - something like an old firewire400 presonus firebox or Avid mbox would work for outputting sound?

    I used a presonus for years via FW with some choice studio monitors. The interface was immediately recognized by Tiger - Plug n play.

    I also used a USB presonus Audiobox with a Quicksilver Powermac running tiger & leopard and it Also was immediately recognized - no fussing at all.
     

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8 May 6, 2019