ef37a wrote:The internal electrolytic capacitors are your best guide to the actual supply voltages. If 16V types (unlikely) for example you can assume 12-0-12 rails, 22V caps mean 15 or 18V supplies but if making a supply from scratch I would not exceed 17V*. For "prosumer" interfaces a 15+15 volt supply gives more than enough headroom.
The current consumption can be estimated from counting the ICs and noting the types but I doubt you will need more than one amp.
The pre USB mouse plug was PS2 (waaaaay ago kbds were 5pin DIN) and they were 6 pins. If at all possible I would change the connector for XLR or 9 pin D sub. Even if space does not permit I would grommet the hole and have a short cable with male line connector.
*D Self: "Small Signal Amplifier Design" gives several 17V schematics and a way to get limited capacity phantom power. Might be easier to just make a separate 48V supply with a suitable transformer?
Many thanks Dave for the most helpful pointers. I have to disassemble the entire enclosure in order to gain internal access, I may be some time!