Instruments before Tyros5 and PSR-S970/770/670/A3000 are NOT compatible with YEM technology.
In other words: Only Genos, Tyros5, PSR-SX900/700, PSR-S975/775/970/770/670/A3000 are YEM compatible.
Tyros 3/4 can use the Custom Voice format .UVN/.UVD and the Yamaha Premium Pack format .YP2 only.
Best regards,
Chris