[44net] PACCOMM TNC-320 Smoke

Hello All, I recently had a power supply problem and it has let the smoke out of my PacComm TNC-320 packet modem. While I have the manual, I do not have a circuit diagram and only have a partial id on one of the cooked ICs U17. The partial number is MC xxxxx06P (I think) and is on the main board across the RS-232 D9 connector circuit. Could you check your circuit diagram, parts list or slide off the cover and have a look and let me know what the U17 IC is please? Many Thanks Rob VK1KW