Hi chip-usa,
It has to be the case that somewhere exessive current is being drawn causing the fuses to blow. Judging from your experiments it is not the DAC/DSP board, so it has to be the interface & PS board itself, the only candidate being the interface logic itself.
Is any single one of the regulators getting very hot (that is much hotter than in your good DSS930)? At least then you know from which regulator (=voltage supply) exessive current is being drawn. Did you already measure each of the voltages (1x30V, 2x5V, 1x-8V, 1x+8V)?
Assuming you have already correctly replaced the hex inverter and the quad opamp, the next step is to replace all the SMD transistors at the back of the interface & power supply board. You may also want to replace the transistor 7406 (BD676) at the front.
Good luck.
Regards,
Dave
