I am attempting to repair a Sonix Ultrasonic Cleaner and I have found that the only parts that have gone bad are two power transistors, SIV300004. I emailed Sonix and they want to sell me the whole control board not just the part. And they didn't want to give me any more info like schematics or a data sheet.

I would need two control boards and they would cost more than this thing is worth. I have searched Google four a few hours and can only find a few references from others from years ago who are looking for the same part. I can't even figure out who makes this SIV300004, If I could I would contact the manufacture. 

So I was thinking that maybe there is some way to figure it out from the circuit. Can that be done? If I were to draw out the schematics would I be able to figure out what specs I would need for a replacement transistor? How would I go about this. Or is there any other way to figure out what I can use? 

Thanks for the help,
Russ