John Jack Masinga was a student at Duduza Sibonelo Secondary school when the 1976 Uprisings started. Masinga, Felix Mpeka and Duncan Mahlangu formed a student movement at the high school they were attending at the time. All three of them were arrested later that year and sent to Robben Island prison.
While Masinga was in prison he was recruited by Mosiuoa Patrick Lekota and the late Muntu Myeza as a member of the Black Consciousness Movement (BCM). A year later, in 1978, he joined the Pan Africanist Congress (PAC) under the ranks of Philimon Chibane and Johnson Mlambo. He served five years on Robben Island for sabotage and was released in 1982, still a member of the PAC.