Thanks Wally! I just tried it with my 2 known working Turbo040's and I get the same screen that comes up when a powercache card is plugged in. Again, with the adapter installed by itself, it boots ok. I have ensured the cards are insulated from the frame too.

The screen looks like this: http://www.flickr.com/photos/gary_w/3400363460/

bummer

Gary

P.S. The adapter card is slightly warped and I wonder if it is just enough to cause problems with the connections of the cache slot to the board itself.