Build a replacement for a broken proprietary AC adapter

Submitted by olaf on 2015-11-05

Yesterday, my tablet (Medion Lifetab P9514) didn’t start anymore, even though it was plugged into the battery charger. The tablet is about four years old and my first suspicion was either the charger or the battery itself. Unfortunately, the manufacturer used a proprietary connector instead of a USB or coaxial power connector. This ruled out testing with one of the many AC adapters I already have.

Looking through offerings at various internet shops and markets and also at the original supplier showed quickly, that proprietary comes at a price. The lowest price was still a whopping 30 EUR for a seemingly simple 12V/1.5A AC adapter, which otherwise would cost at around 10 EUR or even less. Because I didn’t really knew, if the AC adapter was the problem, I was reluctant to spend so much money on this.

I rather rummaged in my toolbox, picking a wire cutter and a soldering iron. I also had a spare coaxial socket, which I planned to use as an adapter for my AC adapter. I cut the wire on the old, presumably broken, AC adapter and soldered it to the coaxial socket. I connected the inner wire (+) to the socket’s inner pin and the outer wire sheath (-) to the socket’s outer connector.

I then connected my tablet to the newly crafted adpater cable and the adapter cable to the AC adapter. After charging the tablet for a while, it resumed operation.

Proprietary plug Coaxial socket


Anonymous on 2017-02-09 13:13:00 +0100

I have the very same situation at hand here. Do I understand it right that the white cable is the positive lead and the black cable the negative?

When I search for the ADP-18TB-A adapter, I get results at, but the connector is not correct.

Anonymous on 2017-02-09 14:16:00 +0100

Never mind my previous question, soldered a car 12V plug on the leads and put it in an adapter; all is fine now, the battery is loading AND we can charge it in the car now.

olaf on 2017-02-10 08:33:00 +0100

Yes, the white cable is soldered to the middle pin, which is the positive voltage in this case.

Nice idea with the car plug btw, I’ll keep that in mind.

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