Found 4 alternatives for ST203C686MAJ03 by KYOCERA AVX. Ceramic Capacitors — Stacked SMD, 6 J-Lead.
CAP CER 0.75UF 900V 6SMD
CAP CER 1.5UF 700V 6SMD
CAP CER 3UF 500V 6SMD
CAP CER 27UF 50V X7R SMD