Jackson, a longtime radio station disc jockey, died of an apparent heart attack Wednesday while driving home from dinner in Los Angeles, friends and radio industry colleagues said Thursday.
"I talked to him like two days ago. J.J. was in a great place," said Mark Goodman, a longtime friend who also worked with Jackson as a 'VJ' when MTV launched in 1981. "It's incredible, so incredibly sad it happened like this."
In a statement, MTV said Jackson's love of music and good humor helped set the tone for the cable music network in its formative years.
"He was a big part of the channel's success and we are sure he is in the music section of heaven, with lots of his friends and heroes," the statement said. "He will be greatly missed."
Jackson's career in broadcasting began in radio. He first gained prominence while working at WBCN in Boston in the late 1960s, then moved in 1971 to Los Angeles where he took on the afternoon radio slot at KLOS.
In the late '70s, he worked as a music reporter for KABC-TV, then it was off to New York and MTV, where his musical knowledge, hewn over years in radio, helped ease his transition to a new format for music, Goodman said.
"It was a great experience for him. He came in already knowing and being successful," Goodman said. "We were all thrust into the spotlight and he was able to take the things that happened at MTV with stride."
After five years at MTV, Jackson returned to radio in Los Angeles, including a stint hosting a nationally syndicated show on the Westwood One Radio Network. Most recently, he was hosting an afternoon slot at Los Angeles' KTWV.
"All of us at The Wave (KTWV) are saddened by the news about J.J.," said Samantha Wiedmann, assistant program director for KTWV. "He was a warm, kind person whose track record in the industry speaks for itself."
Goodman said Jackson had been divorced for some time. He had a daughter and two grandchildren in the Bahamas, Goodman said.