G4 Powerbook Power Adapter

Does anyone have any information on precisely how the LED circuit works?
Jon wrote on :

I recently damaged the plug on my power adaptor (the one that plugs into the Powerbook, and glows in different colours to let you know the charging status). I expected I could obtain a replacement fairly easy, and solder it on the cable but no such luck, they seem to be totally unobtainable.

Any sources anyone?

The Plug glows as soon as power is applied to the adapter, even if it is not plugged into the powerbook. I've now dismantled the plug, and looked for info on the Apple site.

Removing the shield sleeve leaves me with a version of a micro stereo jack plug, connected to the two wires from the power adapter, via a small PCB. Apparently a voltage is also applied to the sleeve, which the PowerBook PMU uses to determine what type of adapter is attached (e.g. different voltage for the 65watt, the 45watt and the aircraft seat adapter). The sleeve also seems to pass voltage into the LED PCB in the plug, that is used to light the LEDs in the right colour (green for charged, amber for charging).

..so at the moment I have a cut down version of the plug, just the stereo jack part, no sleeve. This seems to work OK to power the powerbook, and charge the battery. Seems like the adapter sensor circuit isn't necessary for a power adaptor to work.

Does anyone have any information on precisely how the LED circuit works?

Any ideas if this provides any additional safety to the Mac? (e.g. preventing overcharging or something).

David Lesher replied on :

Jon *remove*in.pwr@redacted.invalid writes:

I recently damaged the plug on my power adaptor (the one that plugs into the Powerbook, and glows in different colours to let you know the charging status). I expected I could obtain a replacement fairly easy, and solder it on the cable but no such luck, they seem to be totally unobtainable.

Any sources anyone?

They are impossible to find; I've looked. Just finding a mating, non-glowing plug, is as well. Macally has a PS-AC4 with a replaceable cable you can hack; they want $17.00 for it.

The Plug glows as soon as power is applied to the adapter, even if it is not plugged into the powerbook. I've now dismantled the plug, and looked for info on the Apple site.

Removing the shield sleeve leaves me with a version of a micro stereo jack plug, connected to the two wires from the power adapter, via a small PCB. Apparently a voltage is also applied to the sleeve, which the PowerBook PMU uses to determine what type of adapter is attached (e.g. different voltage for the 65watt, the 45watt and the aircraft seat adapter). The sleeve also seems to pass voltage into the LED PCB in the plug, that is used to light the LEDs in the right colour (green for charged, amber for charging).

All the adapters are 24v, I believe. the 65W obviously can deliver more current than the 45W. The 45 will run the bigger screen laptop OR charge them, but can't handle both the way the 65 does.

Does anyone have any information on precisely how the LED circuit works?

Any ideas if this provides any additional safety to the Mac? (e.g. preventing overcharging or something).

I'd guess the Mac puts a different voltage on the sleeve, solely for running the LED's. It varies that with the state of its battery...