Well, my Xenon is finally fixed! Thanks for all the help you guys. I had multiple problems. The mpu board was going. The machine kept re-setting. The new Alltek Board fixed that. 2 connectors had to be re-pinned. The coin door volume control had to be replaced. And finally...the BIG problem...the loud hum. (see pic) The capacitor on that top right hand board thingy was replaced and the hum is gone! Life is good!