By Jestine Yong on December 3, 2013 A customer brought this powered speaker for repair. It is a Wharfedale Titan 12’ subwoofer Amplifier. The complaint: No power. I opened the unit checking the usual things such as the fuse, EMI filter coils, voltage on filter caps etc. These all checked out fine, and I measured 320VDC over the two filter caps. The unit uses a SMPS. The smps and class-D Amplifier, are both on the same board. I then connected my analog meter to one of the secondary output lines going to the amplifier. There was no voltage here, and nothing on any of the other output lines going to the pre-amp board. I then proceeded to check if it is a shutdown problem, by switching the unit on and watching to see if the needle on my analog meter jumps up for a brief moment. No movement at all. This made me believe I have a primary –side fault. I checked the two, main switching Mosfets and they were good. From the below photo you can ...