Just built up a board, basic tests showed things to be fine, until I tested the MOSFET output. no matter what they always had and output - and an input. After mush pocking around with a multi meter I found that the board substrate had a voltage by comparison to the 0v side of the battery. There is a resistance between the substrate and the copper too, its high from about 0.9 to 15M ohm.
The batteries supply 6v to the copper, which goes to the MOSFETs and 5v regulator. The board is showing about 3-4v
I have no doubt that I will have to make another board, which will give me a chance to make some minor changes. But this is still really quite frustrating.
Has anybody else come across something like this? It had me stumped for a couple of days.