Printer connected to Mac only works if other Mac is turned on I have an old iMac G5 with Mac OS X 10.5 (Leopard) and a Canon PIXMA MG5350 printer. It prints without a problem on the old G5. I think the printer is connected via bluetooth.

And now I also have an iMac G6 with Mac OS X 10.7 (Lion).

I can print on the printer, but only if the old G5 is turned on. Why?

How can I change this, so that I can print on the G6 when the G5 is turned off?
Probably the printer is connected to your iMac G5 and you are sharing it over the network. If you use this shared printer as your standard printer at the Gen. 6 iMac, it will quit working as soon as you turn off the iMac G5. Connect the printer to you WLAN and configure a new printer at the Gen. 6 iMac.