As I work in repair center, I could not notice many Line6 DT50 amps with short winding in the power transformer (secondary HV). These transformers are currently out of stock. We decided to manufacture new transformers by ourselves as we can make them better than PRC.
The main cause of this fault is bifilar secondary for 2x258V. These wires conduct high voltage and they are located all the way next to each other. Do not wind up secondary as bifilar.
Mains Transformer LINE6 #11-30-0045 datasheet is located below if you want to make your own. We did not, however, count all the turns of all windings as it was difficult without proper tools. You have to calculate the turns by yourself. Anyway, the datasheet gives you a clue about voltages and color codes.
The procedure itself is very simple. The hardest bit was to guess the key shortcut to get into the fader calibration menu.
I have developed this interface in 2011 because I had two M-Audio DELTA 1010 sound cards at the studio, gathering dust. Later, it seemed to be good idea to sell them. But I have never managed to make and sell many ADATERs therefore the price stayed too high.