Maxxarcade demonstrates a QSC A21 Amplifier Repair, the defective amp would blow the fuse on power up. He has an interesting technique of using a variac and a low wattage light bulb in series with the power input to lessen the current draw to prevent additional damage. The over current prevention technique didn’t allow the amp to draw enough power to work properly and sound good but it proved that there were no major shorts remaining. Turns out one of the output transistor was shorted. He now has a kick ass amp that will be driving some book shelf computer speakers! A bit overkill but he will never run out of headroom.