It looks like a temporary suppressor (TVS diode) from Shindengen Electric. Called their series "trankiller".
These transient suppressors all begin with ST03D-XXX where XXX is the breakdown voltage. (T3D -XXX)
If your diode has a position number "D103", then this is a diode "ST03D170".
Download the diagram and see for yourself.
СКАЧАТЬ SONY DVP-NS325,NS330,NS333,NS430,NS433,NS530,NS725P,NS730P :
SONY DVP-NS325,NS330,NS333,NS430,NS433,NS530,NS725P,NS730P.pdf