now, if i use the outer side of the psu plug to ground the _ probe, the same readings are apparent, but, if i let the - probe touch the chassis, it seems to damp the voltages down to what they should be. a small red surface mount led comes on (forward right corner) and a blue led (facing outward from rear centre).
Ah.. waitasec.. blown fuse, I think.
Between the AC-Adapter jack, and the +3.3V jumper, is a flat-ish silver thing. This is a 2.5A fuse, which connects the negative contact of the AC-Adapter jack to the ground of the empeg.
It has two contacts where it is soldered to the board. Measure the resistance across the two contacts (should be zero ohms, but probably isn't in this case).
-ml