My friends dac was repaired 3 times. I think this dac has problems with overheating regulators and all sorounding material. When i glued 4 haeatsinks ont the top it was better. But not 100% solved the issue. One designer wrote that 1704 has problem when supply voltages for dac chip are not present at similar time.Can be that this shunt regulators are turning on differently.My friend bought Denon receiver where 6 dac were in. I replaced 2dacs and 2 times 1. Measure DC voltage on red I/V resistor. It should be 0v. I think on damaged channel was always some dc present. If you need schematic i can send it to you. Try to find denon receiver or dvd or yamaha receiver, if you want to have this dac. You will for sure repair it at some time. Sound....for me nothing special. Best sound was from i2s input. But built like tank 
.
.
Hvala androa
I will check it out. It is not my DAC, just repairing it for a friend. I was never a big supporter of NOS DACs myself TBH. As you said - sound is nothing special with almost any I/V stage I tried - tube, SS, opamps.
I would not mind checking the schematics if you have it handy.
I will check it out. It is not my DAC, just repairing it for a friend. I was never a big supporter of NOS DACs myself TBH. As you said - sound is nothing special with almost any I/V stage I tried - tube, SS, opamps.
I would not mind checking the schematics if you have it handy.
Last edited:
PCM1704 is notoriously unreliable. I never had any device that had these DAC chips but I often read of the problems. Nevertheless I do have experience with other chips that had latch up with supply voltages not ramping up simultaneously. There is a simple solution for that.
I suggest to use 2 antiparallel Schottky diodes (like BAT46) between +Vdd and +Vcc. Of course the same with -Vdd en -Vcc. I do hope the issue is not that the positive lines are ramping up faster than the negative lines.
Last edited: