Law enforcement sources tell us ... Ron died of natural causes at his home in St. George, South Carolina on August 27. A specific cause of death was not disclosed.

Throughout his decades-long career, the veteran actor appeared in several TV series ... including starring in the popular '70s soap "Ryan's Hope" -- in which he played Dr. Roger Coleridge.

The Michigan native announced his retirement from Hollywood in 2010 ... after racking up 2 nominations for the Daytime Emmy Award for Outstanding Supporting Actor in a Drama Series and a Soap Opera Digest Award nomination.

"General Hospital" paid respects to the late actor on social media, posting on X ... "We would like to extend our condolences to his loved ones during this difficult time. He was an incredible actor and an unforgettable colleague. May he rest in peace."

Ron is survived by his nieces and nephews, Lori Brown, Max Brabham, Erin Wilson, and Marc Brown.

He was 78.