I know this is an old thread but I've been sitting on 2 mackie HUIs I got from a warehouse default sale - scratching my head for almost 2 years... neither start up I tried replacing suspect caps but no love... Did anyone ever figure out the transformer specs? Sorry to hijack your board Midibox guys - this is the only active thread I could find on the net... Thanks for tolerating us and thanks in advance to anyone that can help! Holly