I’m working on a Helicon VoiceLive2. It doesn’t power up. I have no schematic. It uses a working DC 12v wall wart. I traced power into unit to a surface mounted blown fuse. From the fuse correct flow goes to device Q800. I suspect it is a transistor but markings are not directing me to any part. I added a photo. It appears that from Q800 voltage goes to a LM317 and a circuit that may be a DC to DC converter (can see several coils and a filter cap arrangement that suggests a split supply).
Thanks in advance,
Fred