Digital voltmeter to measure car adapter
Until there are reverse polarity protected car adapters, a voltmeter is essential to use to protect your valuable notebook from reverse polarity damage.According to the tip, plus should be on the outside and minus on the inside. According to the voltmeter, it is the other way around. From one production series to another one has simply changed the assignment.
Incomprehensible why at all reversible plugs. The last notebook I know with outside plus and inside minus was the Bicom Subnotebook from 1993. But this would have needed 6V and would therefore also be unsuitable for this Car Adapter.