Hmm, ok. Now I'm second guessing myself here. :D
When I designed my unit, I had interpreted from the original manual that the BNC was connected across the HI and LO terminals, like the multimeter when connected.
Now I'm not so sure....
It's not a big deal to configure one way or another, either isolate the BNC shell from chassis and install the wire to the PCB for connection to the LO terminal, or remove the wire and connect the BNC to the chassis.
I think I'll do some testing in each configuration and see what works best. I have a couple TM501 mainframes on my bench ready to be tested right now by chance.
Jared Cabot