Ipod Classic wont charge from the mains

I have had my ipod classic for about 7 years and never had a problem. Still have the original lead and charger but over time have gained two spare charging leads and a third party mains unit. My iPod now wont charge from any mains point using any lead. I have a USB voltage tester and it shows that no current is being drawn.

Using the same leads the iPod charges up from 3 batteries I have for travelling. It also syncs fine with the computer running itunes regardless of which lead I use.

I have two Samsung chargers for my phone and tablet and I have no joy using them either.

All the chargers work fine with every other device

I have reset the iPod using the menu/center button and have done a full restore through itunes.

Any clues would be welcome