Looking at the specs, your monitor just takes composite sync on the S pin (usually ouput via the hsync line, as buttersoft says). The separate hsync/vsync connections are optional, so probably aren't even connected to anything on your chassis.
Interestingly, the specs on the website selling these monitors say "Use The Double Video Amplifier Circuit, Provided Better Picture Quality", which seems to suggest it has a built-in amp, but I'm not sure, TBH.