[Kawai_man]

I have an e-mu 0404 usb that I've been powering with a small variable linear power supply I have, today I had the power supply at 7.5v for something else and I forgot to switch it back to the 6v setting ,  the e-mu turned on an then turned off really quickly, now it doesn't turn on at all. I opened I up to see it just needed a fuse replaced but it doesnt use a fuse, Im wondering if the on/off switch  acts like a circuit breaker  and I just need to replace that? I contacted e-mu but they wont get back to me until Monday. i can take internal pics if needed
 
 
I have experience working on house wiring, I know how to use a multimeter and I can solder

 

[amb]

Most likely you fried some parts in there, possibly including the main microcontroller itself.