Does anyone have experience with moding or repairing Lite audio DAC 83? I have one with a dead channel and it seems to be a common problem. I appreciate any guidance.
There is a strong possibility it is one of the PCM1704's that has gone defective but as Mark said you really need a scope to check it out properly.
Yep - I got a scope and a DMM with a freq counter. Yes, it is a quad 1704 design. I just pulled the boards out of the chassis and will check the output of each of them tomorrow. Any specific tests I should do in addition to that?
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.
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... and just by probing around couple of checkpoints I managed to lose the other channel as well. Not good.
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.
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My dac randomly produces a very low sound from time to time. I mean it is the music but at a very low level.
Any idea what it is? The digital section seems to be functioning properly but the amplifier after the I/V stage does not. Any ideas?
Any idea what it is? The digital section seems to be functioning properly but the amplifier after the I/V stage does not. Any ideas?