"Call me when you finish the homework."
Translation:Ödevi bitirince beni ara.
You could say that sentence however it'd mean something else.
"Call me when his/her/its homework is finished."
Bitmek - to be finished (intransitive, it can't take objects).
Bitirmek - to finish sth (transitive)
if there ıs no personal tense in these sort of sentences do you automatically assume its for sen/senin ?
This is a command, you it must be in the second person. :)
In fact there is personal tense in imperative:
sen ara o arasın siz arayın onlar arasınlar
it is not wrong, it is a missing alternative. However, keep in mind that it would rarely be used
The imperative "ara" already shows that it's second person (Sen). Since Turkish is a pro-drop language we do not need "Sen" at the beginning.
The verb aramak used the accusative case. :)
Because you need to conjugate the "ödev" to match the "senin" :
Senin ödevini bitirince, beni ara