PC Board, I/O Interface, For the ABI 392 and 394 without Trityl monitoring (auto analysis). This is the small board on the right hand side if the instrument. It plugs into the bottom of the CPU Board. Exchange. Since this is an exchange part, you must return your old part complete with all components. If you do not return your part or you return it missing components, you will be charged as though you purchased a new part without exchange. If you do not want to send your old part back to us, you should purchase this same item as non exchange from us.