The thing that makes me think that it was incorrect voltage is that everything on this particular transformer (except the transformer itself) was burned up. This included the controller, the transducers and their power supply, and the amp donuts. There is another controller on the matching unit with the same components and nothing happened to them.

Of course it is hard to troubleshoot the exact cause if you are not on site. We generally always send the customer a new controller ASAP so that they can get the system back on line. Then it is up to service to figure out who pays for it. These controllers have a lot of wiring and it ends up costing somebody a large quantity of money to have one completely replaced.