WM8805 upgrade board (cs8414 pins) - dissapointed - Page 8 - diyAudio
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Old 30th November 2011, 02:31 AM   #71
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by paul_peraic View Post
I have got mine working for now over two hours and then it loses signal lock
That could be software related. The WM8805 has many "undocumented" features and correct software implementation is a major PITA.

Ciao T
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Old 30th November 2011, 02:52 AM   #72
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Hello,

ThorstenL: Thanks, not much left to check since the settings are set via an atmel chip... The cricuit seems ok. Must be a bad setting in the registers.


paul_peraic:
I have the full schematics, but the product delivered is a bit different (single regulator, missing bypass caps in some places, no 75R on inputs, different crystal).


Problem is that all the settings are set via an atmel chip, so no way of knowing if a bad setting is causing the lock issue (and there are lots of settings). Other than the settings, it may be defective, but I doubt it. I have 2 units, both lock but have intermitent errors (error led lights up).

There isn't anything between the input pins and the IC.

PM me and I'll email you the schematics.
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Old 30th November 2011, 03:51 AM   #73
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Join Date: Nov 2002
Hi,

Quote:
Originally Posted by mfrimu View Post
ThorstenL: Thanks, not much left to check since the settings are set via an atmel chip... The cricuit seems ok. Must be a bad setting in the registers.
Maybe restore the Input Amplification with a 3.3V Supply? I can tell you off line how to fix that circuit properly (I do not want to give the CKM's [Chinenes Kopy Mao's] something to Kopy that actually work's).

But if the IC generally locks to a 0.5V P-P SPDIF Signal the register setting is likely proper and the unlock issue is somewhere else.

Ciao T
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Old 30th November 2011, 07:23 PM   #74
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My input spdif + goes from RCA connector to a relay (toslink/spdif) via 3cm of twisted wire from RCA to PCB then to the IC input. The ground is grounded on the PCB. The 75R is right at the RCA connector.

Should I bring the ground of the SPDIF closer to the WM8805?

I wonder if in default hardware mode, spdif in, 12Mhz crystal, i2s out, the WM8805 would work better. Most likely the default settings would be conductive to 'standard' operation.

Last edited by mfrimu; 30th November 2011 at 07:27 PM.
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Old 1st December 2011, 01:01 AM   #75
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The SPDIF input of a DAC is a primary source of common-mode noise and the routing of its gnd potentially has a large effect on sound quality. Therefore I'd recommend not bringing the ground from the RCA input on to the pcb, rather it needs routing away to a star ground. Just this week a DAC I'm playing with kept making intermittent hissing noises, I eventually tracked it down to the receiver losing lock because I'd put a ferrite bead on the ground to the SPDIF input in a misguided attempt to reduce common-mode noise. I've now changed to using a transformer on the input, a resistor to ground to soak up some of the noise and the problem hasn't recurred.
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Old 1st December 2011, 03:08 AM   #76
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by abraxalito View Post
I've now changed to using a transformer on the input, a resistor to ground to soak up some of the noise and the problem hasn't recurred.
Transformers can help a lot, but they carry their own problems. Before Jocko Homo took his leave of this place for his own good reasons he could have told you some of this...

Ciao T
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Old 1st December 2011, 04:32 PM   #77
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Ordering a PCM1704K from HK, 50% that it's a fake. I can't find any other options, Digikey ETA is Jan 19 2012.

Searched Google, but only PCM1704u-k in stock are in HK or China... The IC is in production with 20 week lead times at most suppliers like Mouser, Digikey, NewArk, etc.
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Old 5th December 2011, 01:06 AM   #78
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The voltage regulator for the PLL could be a problem - it's about a 1.7mA load and some vregs need 3.5mA-10mA minimum load current to be stable (i.e. the LM317 from the OP or LT1086 or AMS1117-3.3). I've seen the vreg oscillate or be extra noisy with higher Vout than expected. Not that I would use one of these noisy beasts for top performance.
The output divider adds about 4.2mA load and you could add a resistor to up the load. I find a dedicated vreg for every pwr pin on every IC can be overkill.
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Old 5th December 2011, 02:16 AM   #79
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My CS8414 to WM8805 converter board loses lock after about an hour and a half the lock light starts flickering gradually and crackling starts in the right channel then intensifies after this it totally loses lock the SPDIF input does not have a transformer.

Then I shuffle through the on board input selector and it is good for another hour and a half very strange .

It is very difficult to go back the CS8414 after getting a taste of the WM8805 receiver it has so much more of everything .

Last edited by paul_peraic; 5th December 2011 at 02:26 AM.
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Old 5th December 2011, 02:27 AM   #80
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Quote:
Originally Posted by ThorstenL View Post
Transformers can help a lot, but they carry their own problems. Before Jocko Homo took his leave of this place for his own good reasons he could have told you some of this...
Yes I've followed Jocko's writings with immense interest. He seems to me to put undue emphasis on waveform fidelity and ignore common-mode noise. So he disses (for example) the low interwinding capacitance designs of SC because such buy their low capacitance at the expense of higher leakage inductance.
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