Rabbi Yitzchak Irvin Chinn, the senior Orthodox rabbi in Pittsburgh who during his half-century at Gemilas Chesed Synagogue motivated hundreds of families in McKeesport and White Oak to embrace and study Judaism and live Jewish lives, died yesterday at UPMC Presbyterian. He was 78.

Together with his wife, Denah, Rabbi Chinn arrived in McKeesport in 1958 to head the city's oldest synagogue, Gemilas Chesed (literally, Deeds of Kindness), founded in 1886 by Hungarian Jews. Within a few years, when U.S. Steel wanted to expand, the synagogue was forced to move.

The Chinns chose to rebuild the community in the nearby suburb of White Oak. In short time, there were 300 members. The Chinns built the area's thriving Jewish population further through a four-day-a-week after-school program, plus a Sunday school. Later, a boys' mesivta, or high school, was added in White Oak.

In addition, the Chinns developed unique programs for families. One, called Cherish Your Shabbat, was intended to interest people in observing the Jewish Sabbath, from sundown Friday to after sundown Saturday.

As it grew in popularity, teens from Pittsburgh would travel to White Oak and stay with families for the weekend. Local couples and families would bring food to the synagogue Friday afternoon. On Shabbat, the synagogue would be taken over with classes, meals, services and playing children.

"He had a gift and a pleasantness that I haven't seen in anyone else," said Cindy Guttman, of White Oak, a member of Gemilas Chesed. "His passing is like taking a piece of everybody's heart."

Rabbi Chinn was involved in numerous Jewish and civic programs. As senior rabbi, he was head of the Vaad Harobanim of Pittsburgh, a panel of rabbis dealing with communal affairs.

A brilliant speaker, Rabbi Chinn had periodic offers to leave White Oak. The fact that he never left, people said, was a testament to his selflessness and love for the community.

"He put his life into it," said Rabbi Yisroel Rosenfeld, dean of Yeshiva Schools of Pittsburgh. "The key factor of him was he was liked by the entire Jewish community and beyond."

In addition to his wife, he is survived by two sons, Reuvane, of Toronto, and Hirsh Michel, of Silver Spring, Md.; a daughter, Nechama Landesman, of Los Angeles; two sisters, Baila Kaplan, of Jerusalem, and Raizel Silver, of Toronto; 25 grandchildren; and 31 great-grandchildren.

Services were yesterday. Burial will be in Jerusalem.