My big mistake was assuming that if iTunes could drive the MOTU 828 successfully, then so could Logic, because I'd already proved that when Logic couldn't drive the MOTU, neither could iTunes. Never assume.
So I'm taking a step back and trying to see exactly what variables we have here.
When I first brought the G5 home, none of the Firewire ports worked at all; this despite the fact that they had all been working fine the previous day in the office. Only by unplugging everything including power, leaving it alone for 24 hours and then restarting could I get any Firewire device to work at all.
So, I started again from scratch this morning by switching off the Mac, unplugging every Firewire device (including the 23" Cinema monitor with Firewire bus) and then unplugging the power cable from the back too. This apparently resets the PMU (Power Management Unit?) and you can certainly hear a click as if something just switched off when you pull out the plug.
Tonight it's one step at a time:
- plug the MOTO 828 mk2 directly into the back Firewire 400 socket, and start up the Mac. Yay! Logic runs fine. Create a little two bar loop driving two instances of Ultrabeat, copy the patterns to the arrange window and switch off the Ultrabeat sequencers. So now we've got a little 'ezylode' startup file with two tracks.
- Switch everything off, connect the monitor Firewire bus and then plug the MOTU 828 into the monitor. Start up again. Yup - Heave a sigh of relief. Everything is running fine.
- So far so good. But remember, all the music is stored on the external HD. So next test - while Logic is running, I'm going to plug the external HD into the Firewire 800 bus. Here goes... As the last time, the sound disappears a couple of times but it eventually settles down. Strangely, one of the Ultrabeat tracks is coming and going, fading out and in again in the second bar. No - it seems to be OK.
- Plug the iPod dock into the 2nd monitor Firewire port - and one of the ultrabeat tracks has now disappeared altogether. Unplugging the iPod dock makes no difference. I know, let's try switching it off and then switching it back on again. Well restarting Logic fixes it, and this time, plugging in the iPod dock makes no difference.
- Let's push the boat out. I'm going to connect the portable HD via a Firewire socket on the back of the external HD. Fingers crossed... Whew - again the cutouts, the switching in and out, but stopping the playhead and starting again are enough to fix it.
- And finally, I'm going to restart the machine and see what happens... Jeez - still working. OK, as you were. Back to work everybody. Nothing to see here.
Shit. What was that all about? I think that there is every guarantee that this will happen again. And I'll need to go through the whole diagnostic process and then suddenly the computer will just decide to start working again.