I installed several CD80AE racks in the 1990-93 timeframe and they definitely accepted DMX512. As I recall the screw terminal connectors were located at the top left side of the rack. Assuming your AMX192 connections are still there, I believe that you only need to reconnect DMX on the "Common", C+ (or D+) and C- (or D-) terminals (depending how they're labeled). If the data wiring is intact back to the control booth, you could probably just install a 5-pin male in place of the existing 4-pin, reusing everything but the red (analog mux) lead. I'm pretty sure the AE rack will auto-detect DMX512, but I may have to do a little more research if this advice isn't sufficient.