Compaq CGA card, schematics?

All,? I have a Compaq Portable ("luggable"), revived from damp storage, and I'm trying to work through some of the troubles it has. First one I'm trying to sort involves the video card. It has the original CGA card in, with the internal output hooked to the internal screen. It has a DB-9 connector for an external C/EGA screen and also NTSC composite output on an RCA plug. I've not been able to test the external 9-pin because I don't have a screen, but I'm going to guess it's working because the internal screen display is good. The composite out is terrible. On several television sets it jumps, losing horizontal sync. The image supposed to be on screen is legible, just. Anyone have experience with this issue (a particular cap, a chip particularly prone to failure) or the schematics for the board? It's tough to trace, being a 3 layer sandwich. If anyone has the schematic for the vdu driver board also, I need to work on that too, it's suffering from dry capacitors. Thanks Phil Andrews Sent from my Samsung Galaxy S?4