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Old 13th October 2006, 09:52 PM   #11
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Yes you need 75 ohm in parallel and behind that 10nF in series as input for each S/PDIF input, don't you?
Never heard about the pass labs before, but seems to be a bright field somehow. I will check out more later I guess.
see you...
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Old 19th October 2006, 10:18 PM   #12
cviller is offline cviller  Denmark
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Default Why?

I have made the pcb's for my design, but it doesn't play.

The problem could be related to the fact that I am reusing a cs8416 from an old board. I might have fried the chip with my hot air gun. My supply voltages are all correct, but the there is only static noise (not much) and no music.

I have attached my schematics - if anyone can find showstopper-errors I'll be happy!

I think I'll try with another old cs8416 in the weekend. I guess the only way to sort this out would be using a scope - I think I have to buy one soon, cos it's really annoying not to have one at home.
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Old 20th October 2006, 02:02 AM   #13
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I'd bet on the chip being fried. One question for you. Why does the reset to the DAC have a 100k series resistor and bypass cap? I'm using the same reset chip without anything. By the way, you may want to look at my schematics, if you haven't already. My DAC is similar to yours, and it is working.
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Old 25th October 2006, 01:01 PM   #14
cviller is offline cviller  Denmark
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Default still no progress

I got some cs8416 from digikey today, but I still can't get the thing to play. The schematics is still the same (attached).

I have also changed the 1798 i case it had gotten fried too, but nothing helps. I'm not sure how to go on from here - I have tried to measure for opens and shorts everywhere, but with no luck.

I tried a scope a few days ago, but it was too slow and the probes where no good. Any ideas what to try next? Would it make sense to etch a new pcb and try again?
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Old 25th October 2006, 02:21 PM   #15
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I asked a question above about the reset chip, but you didn't give an answer.

Also, although this probably isn't the problem, why do you have VCOML and VCOMR going through the same cap? They should each have their own.

I'm trying to help here, so please answer the questions, otherwise, that's the last advice I'm giving.
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Old 25th October 2006, 02:34 PM   #16
cviller is offline cviller  Denmark
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Thank you for trying to help!

The resistor and cap was to get the cs8416 clock running before releasing the reset on pcm1798. I have tried to subvert it but nothing changes - I didn't ignore your questions, I was just too frustrated to answer.

On page 18 in the pcm1798 datasheet, the cap is connected to both vcomr and vcoml.

The weird thing is that with the pcm1730 on my last attempt I got some wonderful music through, but with a very similar design, nothing seems to work.
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Old 25th October 2006, 02:48 PM   #17
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Quote:
Originally posted by cviller

On page 18 in the pcm1798 datasheet, the cap is connected to both vcomr and vcoml. [/B]

You know, I never noticed that. The PCM1794 data sheet shows a separate cap for each, and that's how I did it. Well, at least, now I know that is o.k. for PCM1798, too, because my DAC currently has it set up that way. I'll take a closer look at your schematic tonight, and see if anything comes to me. Honestly, though, it could be shorts. I gave one of my boards to someone over a month ago, and he never got it to work.
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Old 25th October 2006, 03:05 PM   #18
cviller is offline cviller  Denmark
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Default Analyze this...

When I turn on the power, the system is quiet, but if I reset the system, (I have removed the 100k and cap), it starts making static noise.
Removing the digital supply voltage does not help, but if I pull out the spdif receiver supply (VA3.3) and reinsert it, the board goes back to the quiet state....

You might be right that it is just some sort of short or bad component - I'm leaning towards that explanation too. Maybe I should just make a new board...
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Old 28th October 2006, 03:29 PM   #19
cviller is offline cviller  Denmark
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Talking ITS ALIVE!!!



It was simply the filter components. I ripped them all off and soldered on some new ones. I suspect the 22nF which I changed from a 1206 to 0805, but might have received some with the wrong values. Now I'm back with the 1206 and it works perfectly!!!

I don't have time to write about the details cos now I have to listen...
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Old 28th October 2006, 04:44 PM   #20
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Default Re: ITS ALIVE!!!

Quote:
Originally posted by cviller


It was simply the filter components. I ripped them all off and soldered on some new ones. I suspect the 22nF which I changed from a 1206 to 0805, but might have received some with the wrong values. Now I'm back with the 1206 and it works perfectly!!!

I don't have time to write about the details cos now I have to listen...
Cool. Get out your camera...

Also, you never showed the schematic for your output stage. What does that consist of?
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