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Origineel bericht door: Albert Emil ,


Idle voltage at 17 Volt instead of 6.8 V after changing MagSafe cable


I replaced my broken MagSafe 1 cable with a [|replacement cable] and get some weird idle voltages:

After desoldering the broken cable from the two pins on the PCB, I checked the idle voltage. My multimeter gave me a reading of 6.84 V which is in accordance to the [guide|6463|ifixit guide|stepid=27890] and [|Wikipedia].

However, after attaching/soldering the replacement cable to the two PCB pins, I get an idle voltage of around 17 V. As far as I understand, this is the regular charging voltage at load, but not at idle. Since I ordered two of these replacement cables, I tried the other one, but got the same result: ca. 17 V at idle.

My MacBook Pro is charging with the repaired cable, but does not light up the green LED inside the magnetic connector when fully charged. I assume that this is due to the power supply not reducing the voltage to the required 6.8 V at idle.

Does anyone know how to fix the idle voltage and get proper charging behaviour?


Apple AC Adapter