Do you have the sync plugged in the same connector as the rgb?
It goes into the one above it.
I used seperate syncs on mine.
If you are using the video amp do the following.
The following copied from utilmarc website.
Almost all monitors, even those which have separate V and H sync inputs, will work with composite sync (generally connected to the H input) A few monitors may need separate H and V sync though. In this case the syncs can be separated by doing the following:
Identify the location on the PCB marked "CUT for H/V"
Cut through the short section of track between the two "half-moon" shapes.
Connect the monitor vertical sync to the connection (white terminal block) marked SYNC
Connect the monitor horizontal sync to the connection (white terminal block) which is unmarked
Later,
dabone