This fix is for Megas that would have had the small blitter board on the top of the CPU without the upgrade.

This jumper replaces the board - you do not need to have the little board installed if you have this jumper in place.

IF you have a T4 timing error  and this jumper is not there. Put it in and it will most likely fix your error.

James Schofield
Bikerbob - on Forums