Hi,

I unplugged a faulty SPDIF cable while the DAC was powered and now i get quite loud hiss with random scratching noises from the right channel. I have eliminated all the other choices and it is indeed the DAC that is causing the problem and specifically the right channel of the DAC. I later found out the SPDIF cable did not have proper ground connection.

The DAC is having the problem even if the dac chip is muted. I don't have the default firmware on board but I am controlling the DAC with custom sw on Arduino, so that is not the problem. I tried without the controller (e.g using default settings), but the problem did not go away. I also tried with different digital and analog cabling, and still no go. I tried, to connect left DAC (balanced) output to right (balanced) input of the amp and vice versa and problem moved to left. Nothing but using another DAC fixed the problem.

The voltage levels on the two Placid BPs powering the analog sections seems to be right and there seems to be no variation in the digital section power either. Music is still playing through the right channel. After playing music for some time the hiss gets quieter for a while when silenced but the weird random scratchy noises are still there. It sounds like the DAC was picking up a radio frequency.

Any ideas what got burned? The DAC chip itself or some regulator, some capacitor in the analog section? I don't see any physical detects in the parts, i might give it another try tho.

My configuration is:
2x Placid BP (early version with your suggested mods on this forum)
1x Placid (early version with your suggested mods on this forum)
Buffalo 32s (spdif mode, firmware removed)
2x 15+15V trafo
1x 9+9V trafo
1x LCDPS (one side used only Arduino)
Arduino Duemilanove