Diode D17 between the two input terminals! model 750 12V!
Does anybody know which diode is this D17, between plus and negative terminals on the phoenix 750 12v inverter? victron energy representatives replied to me that they don't have any more the technical manual of this old top secret product so nobody knows anymore or they do not wish to share this highly important information! 
Where did the diode go to? It will have a number written on it.
It looks, from here, that it conducts if reverse polarity is applied. Maybe that will be a clue.
I don't have a circuit diagram to consult, sorry.
Hi, thanks for your reply, unfortunately the diode is damaged so no number can be found and no measurement can be realized now. The diode is installed where you see the diode symbol in the picture.
