thanks for the reply. but i actually managed to find one myself...after getting a copy the service manual(i didn't had one before). A real gold mine of info i'd say.
The point is definitely not ground - but thanks for your effort anyways, MysTiCy.
I searched for resistor "R7224" in the service manual and located it in the schematic. Then I somehow deduced an alternative point by cross-referencing the schematic and the part placement diagram.