Q: I have a 20 GB 4G iPod. I have changed the battery and done a restore and now it is asking to be plugged into the mains to complete the restore. When plugged into the mains it remains with the plug and socket picture on the screen. Any ideas what I can try?
A: Although the fourth-generation iPod was the first model that could charge via USB, most of the fourth-generation iPods required a FireWire-based charger to complete the restore process.
FireWire power adapters provides 12V of power on a different set of Dock Connector pins from the USB chargers, which only supply 5V. The iPod can therefore tell which type of adapter is being used, and in the case of the fourth-generation iPod will not complete the restore process unless it detects power on the 12V FireWire pins.
Unfortunately, most of the modern iPod power adapters and other charging accessories use the 5V USB charging circuits, which means that you may have a hard time finding a FireWire-based accessory to complete the restore cycle. If you have the original AC adapter that came with your fourth-generation iPod which uses the FireWire cable, then this should be sufficient to complete the restore process. Alternatively, if you have a FireWire to Dock Connector cable and a computer with a powered FireWire port, this can be used as well; the iPod does not need actual AC power, but merely the 12V supplied via the FireWire charging circuit.
Ironically, with Apple having discontinued 12V FireWire charging support in most of this year’s iPod models, those remaining accessories that still use 12V FireWire power are becoming more easily identified. Many car chargers still use the 12V FireWire power (since a car natively outputs 12VDC from its electrical system), and many of the older iPod speakers such as the Bose SoundDock and iPod Hi-Fi also charge using the 12V FireWire circuit.
If you do not have a FireWire-based charging accessory handy, your best option is to visit an Apple retailer who may be able to assist you, either via their technical support or simply by allowing you to connect your iPod to a display model accessory that might be able to provide the 12VDC that is required to complete the process. Once the FireWire power is connected, the restore process should complete successfully within a matter of seconds, so you really just need to plug your iPod in briefly to an accessory that can supply the 12V FireWire power to allow it to complete the restore process.