MacBuild Tips 'n Tricks

Audio setup on Digital Audio/Quicksilver

Sometimes when installing Ubuntu on G4 Digital Audio or Quicksilver models, audio doesn't work. No sound comes out under any circumstances, and attempts to open sound controls report that no audio device is present.

The last two generations of G4 Tower models use audio hardware nicknamed Tumbler, and use a special audio output jack that provides power to external speakers. One result of this is that special speakers designed to be used with these machinex are required. Another result, one that concerns us here, is that Ubuntu installation may fail to find any audio device. In that case no audio module is configured and alsamixer parameters controlling audio output are wrong.

To check that no audio device has been detected, you can run alsamixer from a terminal command line, or double-click the speaker icon in the top menu bar (the icon may not be there if no audio device was detected). In either case, you should see some kind of error message or advisory saying that no audio device is configured or detected.

To detect the audio device one-time, on a terminal command line type

sudo modprobe snd-powermac

If that didn't complain, you should shortly see an advisory in the lower right corner of the display indicating that a new audio device is detected.

To make that happen at boot time, edit the file /etc/modules as root (sudo) and add snd-powermac as the last line. Here is an example with the line added:

# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.

lp
snd-powermac

The one you edit may be slightly different, and may not have any other module names at all.

At this point there might still be no sound coming form the speaker during a sound test. Use these commands on a terminal command line to modify the audio driver configuration:

sudo amixer sset 'Auto Mute' off
sudo amixer sset 'PC Speaker' on

To make this happen at boot time, edit the file /etc/rc.local as root (sudo) and ad the two lines

amixer sset 'Auto Mute' off
amixer sset 'PC Speaker' on

at the bottom.

CD Audio Skip

iMacs/PowerMacs with CPU speeds of 40MHz or less and with older CD drives seem to have problems playing CDs using SoundJuicer and RythmBox, the CD ripper and CD player installed by default with Ubuntu. Playback audio will 'skip', producing gaps of a few seconds, and may even cease altogether. Loren has been able to solve this by replacing CD drives in slot loading iMacs and PowerMac Towers. Replacement drives are not always available for iMacs, however. Another solution is to install gxine from the Applications->Add/Remove menu and modify some of its configuration parameters.

gxine configuration parameters are found in the user's home directory, ~/.gxine/config. There may be a global/default version of this somewhere but I haven't looked for it. The parameters for tweaking are media.audio_cd.drive_slowdown, default 4, revised to 0 or 12, and engine.buffers.audio_num_buffers, default 230, revised to 500 (maybe unnecessary). It turns out there is also a visualization parameter there, which can be set to do nothing: gui.post_plugins.audio_visualisation, default goom, revised to None. These revisions make the default operation permanent.

The remaining issue is how to make gxine do the right thing as the default audio auto-startup application. Default preferred applications can be modified through the System->Preferences->Removeable Drives and Media->Multimedia menu. In the Audio CD Disks command box, replace the existing sound-juicer -d %d entry with gxine cdda:/ , which works for commercial audio CDs.

The modified sections of ~/.gxine/config look like this:

• for cd_drive.slowdown

# slow down disc drive to this speed factor
# numeric, default: 4
#media.audio_cd.drive_slowdown:4
media.audio_cd.drive_slowdown:12

• for audio_num_buffers

# number of audio buffers
# numeric, default: 230
#engine.buffers.audio_num_buffers:230
engine.buffers.audio_num_buffers:500

• for audio_visualization

# Default audio visualisation plugin
# { None  fftgraph  oscope  fftscope  goom }, default: 1
#gui.post_plugins.audio_visualisation:goom
gui.post_plugins.audio_visualisation:None

<still needs a set of step-by-step cli instructions - tr 15may07>

Keyboard shortcuts

• Keyboard shortcuts at Apple

Laptop/Notebook recycling

Laptops and notebooks that are to be recycled should have the hard drive and battery removed and the display separated from the rest of the body. The hard drive goes to advanced testing, or can be permanently disabled by MacBuild before recycling. The display does not need to be removed from the cover, and goes into a Gaylord (Huge Cardboard Box) currently right outside of the Black Hole. The rest of the body needs no further disassembly, and goes in a Gaylord currently beside Monitor Testing. The battery goes into the battery recycling mailer carton, sealed in a plastic bag (should be some in the carton).

Power supply testing

There is no tester for Mac power supplies. Apple publishes power supply testing manual procedures for some PowerMac towers:

• PowerMac G3(B&W) and G4 tower Power Supply Testing
• PowerMac G4(Gigabit Ethernet) Power Supply Testing

This link, MDD Power Supply Mods, indicates that the Mirrored Drive Door PowerMac (G4 MDD Quicksilver) is different from other Quicksilver models.

Time since last check message shows huge numer of days at boot

Sometimes after installing a repicated hard drive into a refurbished Mac, the boot process will report (in white text on a black screen) that a file system check has not been performed in several thousand days, usually referring to /dev/hda3. This is a failure in the replication process somehow, and should really be fixed in the replication script. There is a relatively simple command line fix. Use the command tune2fs to set the superblock information on the disk partition to today's date. Here is an example:

sudo tune2fs -T 20070530 /dev/hda3

The date part is a six digit string in the form YYYYMMDD (yead, month, day), and the partition is the one mentioned in the original boot time message. You can verify that the last check time has been updated, also using tune2fs like so:

sudo tune2fs -l /dev/hda3

Look ffor the line that says Last checked:.

Ubuntu splash

A normal CD installation of Ubuntu may result in the normal Ubuntu startup splash screen not being displayed. When the system is first booted after installation, the display remains dark for a long time until the small rotator 'waiting' icon appears right before the login screen. This could give the impression that 'nothing is happening'.

The fix:

1. edit /etc/usplash.conf (with nano or vi)
2. change xres=800 to xres=1024
3. change yres=600 to xres=768
4. save and exit
5. on the command line run sudo update-initramfs -u'
   • this takes about a minute
6. on the command line run sudo ybin -v
7. restart

This fix should already be applied in the hard drive replication images. It has never been made to work with the 17" Studio Display ADC monitors, whose default resolution seems to be 1600x1200.

Video setup on Flower Power iMac

iMacs with 500MHz, 600MHz, and 700MHz processors, the so called Flower Power models, have a 750cx version CPU and ATI Rage 128 Pro Ultra video controller. After a normal Edgy alternate CD install, video response is extremely sluggish. For example, mouse cursor movements lag several seconds behind physical mouse movement.

A fix is suggested in http://ubuntuforums.org/showthread.php?t=191080. It consists of the following changes to /etc/X11/xorg.conf:

• in the Module section

Section "Module"
# Load "i2c"
# Load "bitmap"
# Load "ddc"
Load "dri"
Load "extmod"
Load "freetype"
Load "dbe"
Load "glx"
# Load "int10"
# Load "type1"
# Load "vbe"
EndSection

• in the Device section

Section "Device"
Identifier "ATI Technologies, Inc. Rage 128 Pro Ultra TR"
Driver "ati"
Option "UseFBDev" "false"
Option "SWcursor" "true"
Option "ForcePCIMode" "true"
Option "XAANoOffscreenPixmaps"
EndSection

The normal way to apply these changes is

1. CTL+ALT+F1 to use a virtual terminal (command line interface)
2. login as oem
3. command: sudo /etc/init.d/gdm stop
4. edit /etc/X11/xorg.conf, for example, sudo nano /etc/X11/xorg.conf
5. modify the Module and Device sections as indicated above
6. save the file and exit
7. command: sudo /etc/init.d/gdm start

The normal Ubuntu login page should appear with much better video response.

Note that the original problem is observed in Ubuntu Edgy (Release 6.10).  ATI video
driver installation is different in Ubuntu Feisty (7.04), in that a best driver version
is selected to match the detected video controller.  The problem may not be present with 
Feisty, but that has not been tested as of 15May2007.