tephillin -- part 3

Question

in the last 2 Q&As regarding tephillin you said the mitzvah was not fulfilled b/c the shel yad was later found to be pasul. what about the shel rosh? was that mitzva not fulfilled? or is it one mitzva with 2 parts, and since one part is pasul then the whole mitzva is lost? thank you for clarifying.

Answer

Answered by Aaron Abadi

Each one is a separate Mitzva. My guess is that the other was not 100% either. The subject is found in Shulchan Aruch Orach Chaim Siman #26 AA