If you've been around portable technology for a while, you'll find out that the connection between the external power adapter and the device itself is all too often the weak point in the power system. It can also be hard to find replacements for older power adapters. (Given that the adapters are often black generic units, they often migrate off in a corner, get their tails tangled up, and get thrown in the trash because they are a hopeless mess.)

Here are a few factoids I have gathered over time, with suppliers and part numbers where applicable. In supplier terminoligy, the "jack" is the nominally female part built into the main device, even if the jack has a center pin. "Plug" is the nominally male part usually found at the end of a wire. If you keep the electric guitar arrangement in mind, you'll do OK. (The jack is in the body of the guitar, the plug is on the cable.)

Device / original adapter wattage / Jack diameter [supplier and part] / Plug diameter [supplier and part]

Apple Emate 300: 

• Original adapter: 7.5 vdc, 9w, center positive, Apple Model H0165 (ADP-9AB)
• Jack:
• Plug: 4.75mm (5mm) OD with 1.5mm pin / Jameco

Early gray Powerbooks, such as PB 150, 160

• Original Adapter: 7.5 vdc, 45 watts, center positive, Apple Model
• Jack: 6mm ID, with 2.0 mm center pin
• Plug: 5.5mm OD, no center pin

N.B.: The two next generations of power adapters that follow share similar characteristics. Actual power is transmitted through a standard three-conductor plug. The 3-conductor center plug is surrounded by a thin steel shield. The shield (and the tip of the plug) carry no power. The "root" ring carries ??, the middle ring carries ??

The power jack in the Dual USB iBook is carried on a small circuit board that it is eaily swapped out. Regrettably, the jack itself is an Apple-proprietary part made by Foxconn that can only be obtained by Apple-approved vendors. So, it seems that for now we are restricted to scavenging.

"First Generation" power adapter for G3 Powerbooks and iBooks, such as Wallstreet, Pismo, Clamshell

• Original Adapters: many, many models, all variants on the same theme. [Black brick] Apple model Mxxx, RECALLED [Yo-Yo's] Apple model M7332, 45 watts
• Jack: 3.5 mm stereo jack, with shield.   Male stereo plug, Digi-Key CP-3502-ND
• Plug: see "Dang that Plug!" below

"Second Generation" power adapter, for DualUSB iBook 12" and 14", ....

2.5 mm stereo jack, with shield. 65 watts max

Dang that plug!

The power input plug on the iBook line has proven to be exceedingly prone to failure. Sometimes the flaw is mechanical, sometimes it's electrical.