On Fri, Nov 14, 2014 at 3:58 PM, Roe Peterson <roeapeterson at gmail.com> wrote: I just took a look at a 70-27975-01 11/93 SLU panel that I have and these are the pinouts that I found. SLU 1 - SLU 7 - DB9 Pin 1 - Chassis Ground Pin 2 - SLU Output / Transmit Data Pin 3 - SLU Input / Receive Data+ Pin 7 - Signal Ground All other pins No Connection Console - DB25 Pin 1 - Chassis Ground Pin 2 - SLU Output / Transmit Data Pin 3 - SLU Input / Receive Data+ Pin 4 - connected to Pin 6 Pin 6 - connected to Pin 4 Pin 7 - Signal Ground Pin 20 - +12V Fused (through a 750 ohm series resistor) All other pins No Connection All of the Receive Data- signals (J1-7, J1-17, J1-27, J1-37, J2-27, J2-37, J2-47, J2-57) are connected to Signal Ground. There is a P6KE15CA TransZorb transient voltage suppressor between each TD and RD+ signal and Signal Ground, plus another one between Signal Ground and Chassis Ground (17 of those total).