Most Tri-Sync monitors switch automatically between 31kHz, 24kHz and 15kHz video, unfortunately they cannot switch automatically between Jamma level RGB (high-impedance), and VGA level RGB (low-impedance). The solution provided by the manufacturers is either
- Dedicated connector for high-impedance video (most common)
- High/Low impedance switch (pretty rare)
Some tri-sync monitors also have issues with the composite sync signals from some games, most notably Taito F3.
To make this a little easier, you can order this add-on board that plugs directly into the Jammafier. It performs two functions:
- RGB attenuation and re-amplification
- Sync separation and re-generation
It transforms the video from high to low impedance, and also cleans and separates the sync from Jamma into horizontal and vertical sync. This way you will only need one video cable, and no switches to worry about. It should also take care of most sync problems. It is important to note that it does not change the scan rate - you will need a scaler if your monitor does not support 15kHz Jamma video.
The Tri-Sync Helper is only available as an add-on to the Jammafier and it's only intended use is for Tri-sync monitors.
Powering the Tri-Sync Helper
The Tri-Sync Helper is powered via pin 9 on it's input connector. The Jammafier can deliver this if the jumper "Enable 5V via VGA" is closed. Jammafiers shipped without the Tri-Sync helper has this open. A blob of solder will enable it.