Murphy, I re-read your previous post and I see you mentioned that the only thing you have the 5v supply for is the Opto boards? What I usually do is feed these from my PC supply 5v, preferably source from one of the PC DC supply plugs, rather than via the ICM2900 5v output source, and wire them to the +- supply connector on the G4 Opto board. This should also cure your dim LED
condition.
My reference to the home built supplies etc was to be aware that some times it pays to check the supply design as to wether it is electrically OK to ground the common.
Al