After many hours going over this board with the DMM checking continuity, i have finally found the problem, as i originally thought, it was a broken trace where the previous repairer had changed a chip and put in a socket.
There were 4 re socketed chips all up.
I went through the schematics with both sound boards, and compared the findings with the working board.
Hooray
i have repaired the trace and the board works 100%
thanks too those who offered help with this problem
Ian
