I could not get my new WD 250 GB External to mount on my Powerbook G4. I followed all instructions and then searched the web for answers. WD support suggested it could be a firewire problem with the G4. It powered on but was so quiet I could not hear it spin up. Next I tried to mount it on my PC with no luck. Then I pulled out a three year old WD 200 GB External with my photo archive that was last mounted 6 months ago. I used the same power supply from the new drive and it would power on but not spin up or mount to either the PC or G4.
Next I switched to the old power supply from the WD 200 GB drive and both drives powered on, spun-up and are working flawlessly so far.
What threw me off was the fact that I was using a new power supply and both drives powered on[ so it was only by chance that I discovered the new power supply is bad. I live in Thailand and brought the WD 250 over from the States so today I will hunt around locally for a replacement power supply.
I hope this helps anyone with a similar problem.
nhigear