[Coco] How do you hook up a CoCo 3 to an Amiga 1080 Monitor using the Analog RGB Port?

[Bert & Peggy Schneider]

I bought an Amiga 1080 multi-sync monitor via E-Bay to hook up to my
CoCo 3.  I noticed that the analog mode requires a composite sync.  I
built a simple circuit to combine the horizontal and vertical sync
signals of the CoCo 3 using a 74LS86, but I'm still having trouble.  Any
suggestions?

Thanks!

Bert