'CSI' Star Jon Wellner's Wife Is Flat Broke ... Needs Money ASAP in Divorce

"CSI" star Jon Wellner's estranged wife is desperate for money, claiming he's completely cut her off from their cash and credit cards ... leaving her with only $70 to her name.

According to new legal docs obtained by TMZ ... Whitney Wellner is asking for emergency spousal support because she can't make ends meet after losing her job at a dog rescue ... where she made $11 an hour.

Whitney says Jon makes a fortune -- nearly $114k per year in acting residuals alone -- and she wants a piece. Worth noting, Wellner appeared on 126 episodes of "CSI" over 10 years.

But Jon says Whitney's way off base, because he took a "huge loss of income" when "CSI" went off the air. He says he's now only working on random projects.