Blocking 31KHz, pass through 15KHz?

[StarCreator]

Sort of a long shot, but I'm trying to find out if there's a relatively inexpensive way to create a device that can be added inline to VGA that will pass through 15KHz signals unaltered but block 31KHz. I have a couple arcade cabinets that are being fitted with newer games which briefly output 31KHz until the game logic starts, which I don't think is great for the monitors in them :/

[Xyga]

The J-PAC does that and more stuff you don't need, but it's a bit expensive @ $59: http://www.ultimarc.com/jpac.html

I'd be interested in a cheaper alternative/schematics as well, for my soft15Khz setup...

[Fudoh]

out of interest: do you know how the J-PAC's 31 to 15khz conversion looks like ?

If required, can divide a 31Khz VGA signal in half so that it will display a stable picture on a 15Khz arcade monitor. Useful for checking boot-up progress and configuration (not for application use). Automatically stops dividing the signal when it detects a correct 15Khz rate is being send by the PC.

[Xyga]

Nope. $59 is a bit much when I can just wait a minute anyway, so I've never bought one...

[StarCreator]

Yeah, I was hoping for something smaller than that also...