My BIII with only 1 input level converter board works ok, but after change to the 4 input boards I don't get lock.
I tried power with only 4V without success.

Debugging the problem, I notice that output D1 and D3 of 4 input board are short circuit with ground.
Due I don't find the source of problem, I unpopulated all the board, but remains the short circuit of outputs D1 & D3.
Board has only connected the MAX9201. Do you think the MAX is bad?

Thanks