As I mentioned in 1:1, D1 and F1 are the components that provide +5v feeds for the wire on both connectors that would be used by termination devices (if another device was not already putting +5v on the line). If you run into termination problems with the external termination widget, check the signal line for TermPower for 5V.
The reason these components were left off is because multiple power supplies of different design, and means to rectify source AC (plus phase-differences as inputs), could result in some messy back feed situations that would result in burned traces or a cooked wire on a ribbon cable. I've seen burned-out silicon diodes, and 50-pin ribbons burned down (nearly) the middle when it happens.
Active termination is a better solution to address less than ideal electrical conditions, with the later generation of LVD (Low Voltage Differential) SCSI a much more ideal termination and signalling format - although electrically incompatible to operate at the same time on a SCSI bus as the older 'High Voltage (0-5V), Single Ended' format of most Amiga SCSI interfaces. (LVD uses +/- 3.3V on paired signal wires, and requires the active termination format.)
Rob
