Originally Posted by
stonic
Well I can't take credit for someone else's words. The information is in the Vectrex FAQ if you want to paraphrase it.
And you can't ask an opened-ended question like "why doesn't my monitor work?" and expect a specific and concise answer. Aside from some basic reasons, you'll soon get into a component-level discussion (involving meters, soldering, etc.) that is dependent upon the make and model of the monitor in question. Randy Fromm has a set of flowcharts that cover most of the problems you'll run into, for most of the more popular monitors found. But chances are if it's not related to some of the reasons I mentioned, the person is likely better off contacting someone locally with more experience.