Chosen Solution
My power supply stopped charging. I noticed the wire broke from the transformer, I.e. the 16V DC. So i cut it and resoldered it. However like a complete imbecile I switched the wires, i.e. + to -, and vice versa. I coonnected it to the mac, and no charging light was showing. It was only then on reinspection I noticed the error and rewired correctly. It seems that the transformer has voltage, but on connection to the mac there is no charge light. The computer works, albeit rapidly about to have no battery charge, but … ?Have I damaged the charging circuit somehow?
Most likely yes, The system was not designed to support or reject reverse power. You also have a single wire sense logic which communicates between the charger and system to regulate it which is sensitive to being shorted. Throw the charger away and then visit either an Apple Store or Apple authorized service center to have them check the system. Get an estimate first! As you didn’t tell us which series you have I can’t say if Apple Store will service it they don’t service the older models anymore. The AAS will often still service them, but up to a point. Good Luck!