A discrete component called D313, three pins, can't find it in farnell, what is it ?
If it loks like a transistor, it might be one. Brobably an 2SD313, because transistors stamped D###(#), usually means their real name is 2SD###(#). (With "#" I mean any digit)
Hmmm... One other way of interpreting it: If the D313 is written on the PCB (and not on the device), it's just a placement identifier and will bear little resemblence to the part number. It would just mean something like "Board 3, Diode 13". But if it's written on the actual device, then go with GK's advice. Ben ~~~