The most likely point of failure would be an extension cord. They are sometimes very tricky to pin down as they may work fine in some positions and intermittently if cord is bent a little differently. I would look there first if you are using an extension cord. If you are not using an extension cord-get one. The inexpensive cord can take the pulls and twists that happen when you move the dog around. Better to have a cheap extension cord take the strain and fail rather than putting stress on a more expensive component like your power supply. If the problem is your VVPS, the link to the Tekpower HY 1502 is a solid choice. I have been using one for over 3 years with no problems. Dial is a little finicky and displayed voltage may not agree exactly with your volt meter. The reading will give you a point of reference even if it constantly reads .1 V lower than your volt meter. You will need lab style wiring setup tp connect the Tekpower VVPS to dog. Talk to Underdog about the needed wiring and banana plugs necessary. Good Luck!