Is there anything to split a video signal into vertical, horizontal & blank?

[vol.2]

The LM1881 outputs Vertical Sync and Composite Sync, but it does not output clean Horizontal sync. However, the Composite Sync will be okay for most purposes in a CRT driven signal path.

A device that can just do this for you off the shelf is the Sync Strike. It uses an LM1881, and it outputs over a DE-15 connector, which is the same as a VGA cable output.

If for some reason, you absolutely require clean H sync, you can build a small circuit that gates the vertical portion from the composite sync by using the timing from the vertical sync output. Some PVMs might be picky about this, it depends. Some of them might not take composite as h sync at all, and some of them might show signs of horizontal jitter, or flagging at the top of the screen. It really depends on the monitor.