I have 150 3 year old Tiny PCs, and the PSUs are starting to give up. The only information on them is MODEL: PTP-2028 Made In China. I could get generic replacements, but as we are a school with limited funds, I would like to be able to repair them (I am a qualified electronics engineer). Does anyone know who the manufacturer is, or where I might get a circuit diagram from? Tiny were no help at all!