Apple Powerbook Powersupply Woes

April 17, 2009 9:03 AM

Received a replacement power supply for my Powerbook G4 today. The Apple power supply stats are "Input: AC 100-240V 50/60HZ 1.5A Ouput: 24.5V === 2.65A" The replacement supply reads "Input: 100-240V ~ 2.0A, 50-60HZ Ouput: 15-24V === 4.3A & 75W MAX". Is the new power supply incompatible with my Powerbook?

I plugged in the new power supply in and it began charging my laptop. However, there was a slight wine from below the middle of the keyboard near the screen. Obviously I don't want to fry the thing. Should I return this one and order another from a different source?

posted by jofuu to Computers & Internet (4 answers total)

The supply you purchased is rated for half a volt less output than the previous supply, which really shouldn't be a major issue. It's also capable of twice the amperage - The maximum wattage the Apple supply was rated for is 65, less than the new one.

So technically, it should be OK. If it's making your computer make funny noises, though, I'd return it on principle.
posted by Rendus at 9:45 AM on April 17, 2009

If the numbers are right it should be fine. However, if this is a knock-off you picked up on eBay there is reason to suspect the power supply may not be delivering on its promises.
posted by chairface at 10:09 AM on April 17, 2009

It's hard to say how critical that half-volt could turn out to be. A lot depends on how the brick is built. In cases of big current draw (for instance, spinning up a drive while charging the battery) the brick could brown out, causing the computer to shut down. That half-volt is likely most of the safety margin.

It'll probably work, but it's not what I would have chosen.
posted by Chocolate Pickle at 10:14 AM on April 17, 2009

The weird thing about the 15-24V is, how does it know what voltage to supply? Is the power supply designed for multiple types of laptops? Is there a switch on it somewhere? Or is "15-24" a way of saying "Unloaded, it's 24, but when you load it, it dwindles to 15" which would, of course, be bad bad bad. (I had a 3rd party power brick that acted like this... it said it was "9v", but the voltmeter read anywhere from 5 to 14, depending on load.

Sorry to answer your question with more questions...
posted by blenderfish at 11:16 AM on April 17, 2009