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I am looking for some suggestions on what I should look at next. Output from TOSLINK directly is 2.6V as shown.(#1) Output from 4 input SPDIF board is 4.4V as shown (measured at input D1 of Buffalo III). (#2) Sync is random, never stays synced for long. Picture shows several syncs over 12 second period. (Measured at Sync LED)(#3) I have tried various settings of dip switch, but there is no change in sync behavior. Is there anything else I should consider? Help is greatly appreciated. Edited by user Thursday, March 1, 2012 7:28:08 PM(UTC)
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0) Is 4 input spdif board complete -- i.e. all resistors and wire connections for RSx. 1) The cable between 4 input spdif board and buffalo should be as short as possible (less than 5cm). 2) How is your DAC grounded? Try to measure resistance between power ground and signal ground. It might be an issue if the value is different from 0 Ohm or Inf Ohm. Edited by user Saturday, March 3, 2012 1:05:45 AM(UTC)
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I appreciate your reply. 0) The board is complete, with correct values for resistors based on input type. 1) Yes, I have seen numerous comments about cable length. The scope shows solid signal to DIII. 2) DAC is grounded via Placid PSU. 0 ohms to ground at every point. I did start backtracking with voltage inputs. Note: all Trident voltages are correct. I did find an interesting phenomena when adjusting CSS on placid (VR1). If I back down from the ~500mA setting, the lock would be more consistent and for longer periods (as shown below). The CSS current would be around 420mA, but the voltage was now sagging (around 4.6V) and could not be adjusted up (VR2). The shunt current would be zero. Turning the current back up would cause for the lock to be more random (as shown in the original post). When CSS set back to ~500ma, the shunt current would around 46mA. Now I am wondering if there is something up with the PSU or if there is something on the BIII that could cause this. Any ideas? Help is really appreciated. Edited by user Saturday, March 3, 2012 6:43:32 PM(UTC)
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Next bunch of ideas what to check...
3) Check again if tridents are not accidentally swapped.
4) Try to set ON the 5,6,7,8 DIP swiches on SW1 - maximum jitter tolerance.
5) Is the Buffalo III powered by ~5.25V?
6) What is the sampling frequency of signal coming into TOSLINK? Does it work with 44100kHz?
7) Does it behave same when you connect TOSLINK output directly into Buffalo's input? (i.e. without 4ch SPDIF)
8) Was the optical output from CD/PC/... working with other DAC?
9) Try to test it with SPDIF signal (non-optical).
10) Photo of your setup?
11) Using the scope check Trident output if the voltage is stable.
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Adding a simple voltage divider to get the TTL level TORX output to consumer level before going into the SPDIF4 input module may resolve your issue, but I have not had to myself. :) Edited by user Sunday, March 4, 2012 6:55:38 AM(UTC)
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miero - thanks for replying. Here are the answers to your suggestions: 3) I did this when building, but corrected before this issue started. 4) I have set dip switch 1 with 5,6,7,8 positions changed to ON position. 5) Yes, Placid HD and set to 5.25VDC. 6) I have tried both sampling frequencies (44.1 and 48) No changes in observations. 7) No, when the TOSLINK module is connected directly to BIII, sync is stable. 8) Yes, optical syncs with my Apogee DA1000. 9) Tested with only SPDIF (non-optical) I have. Very low signal ~500mV pk/pk riding DC offset. (By the way, this syncs with DA1000) 10) See below in first picture. 11) Trident voltages are all stable. Picture#2 is the electical SPDIF input to 4 channel SPDIF board (blue) and input to DIII D2 (yellow). Picture#3 is the optical SPDIF output of TOSLINK module (blue) and input to DIII D1 (yellow). With these suggestions it sounds like you are pointing to the 4 channel SPDIF board. But my question is why would a ~2.6V signal (like shown in my first entry, first picture sync up, but the output of the 4 channel SPDIF board with a ~4V signal not? (unless there is something incorrect about the signal itself). Since I can find no discussion of the expected output of the 4 channel SPDIF board I am inclined to think there is an issue with this. (Russ can you address?) Can someone confirm or suggest something else? Comments are appreciated. Edited by user Sunday, March 4, 2012 6:14:20 PM(UTC)
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The first thing I can see off hand is a very long ribbon cable. It should be about 1/8 that long. Move it right behind the DAC. Edited by user Sunday, March 4, 2012 6:29:52 PM(UTC)
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Also it would help to connect the -IN and GND for the TORX input on the SPDIF4. I am surprised it comes anything close to locking at the moment. Not trying to be rude, I am just truly surprised. :) You actually may be able to keep the ribbon as it is if you just fix this. :) Edited by user Sunday, March 4, 2012 6:30:44 PM(UTC)
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Russ, thanks so much for replying. No rudeness assumed! I am interested in why the lower signal (2.6V) would lock (with no ground connection from the TOSLINK module - shown as the very first picture included in this thread) and the SPDIF 4 (with a solid 4V signal AND ground - shown as the very last picture in this thread) would NOT lock. What do you expect to see as the output of the SPDIF 4 board? Do you have examples you can attach? Another item of interest is the electrical SPDIF signal will not lock at all (through the SPDIF 4 board). I have taken your recommendations into consideration. When I was testing before, I have had no more than 1 inch between TOSLINK module output and DIII input and had things working, and then changed that to a 20 inch connection and had things working. The important point I want to note is that ANY connection that goes through the SPDIF 4 board DOES NOT WORK. So that I can troubleshoot this board, what can I do? Is it time to replace this board? Edited by user Sunday, March 4, 2012 8:42:17 PM(UTC)
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I agree with Russ about the long ribbon cable. The TTL voltages are in the ribbon cable too! It's good that TOSLINK module is stable even on longer distances, but the 4ch input module is not (maybe because there are 4 channels close to each other). You have probably saw my pictures, but please check again: doesn't lock - similar issues like yoursdoes lockEdited by user Monday, March 5, 2012 12:48:33 AM(UTC)
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The reason that the TORX worked directly with the DAC is that the TORX and the DAC shared a common ground. If you connect a source to the SPIDF4 board you need to be sure that both ends of the input transfomers are connected to the source. So for TORX that mean -IN to TORX GND and +IN to TORX OUT. The same goes for all of the other inputs. -IN to SPDIF return(sometimes GND) and +IN to hot. GND is only used as a separate signal in the case of AES input. The key is that both -IN and +IN must *always* be connected to something. Edited by user Monday, March 5, 2012 6:00:17 AM(UTC)
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The key point is that your consumer and TTL level SPDIF inputs should not be connected to the SPDIF4 +IN and GND, but rather to +IN and -IN. Only AES should use all three. Non-AES will not use the GND terminal at all. In the case of your TORX module because it is sharing a power GND with the DAC you can simplly tie that GND and -IN together at the SPDIF4 input. Edited by user Monday, March 5, 2012 5:56:00 AM(UTC)
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"I did start backtracking with voltage inputs. Note: all Trident voltages are correct. I did find an interesting phenomena when adjusting CSS on placid (VR1). If I back down from the ~500mA setting, the lock would be more consistent and for longer periods (as shown below). The CSS current would be around 420mA, but the voltage was now sagging (around 4.6V) and could not be adjusted up (VR2). The shunt current would be zero. Turning the current back up would cause for the lock to be more random (as shown in the original post). When CSS set back to ~500ma, the shunt current would around 46mA."
bssanders:
I experience a similar phenomena to what you have described, using input via Toslink module to S/PDIF-4 board Input C, and nothing on the other inputs. Lowering supplied voltage out of the Placid to around 4.6v or 4.7v seems to stabilize lock. Gradually increasing the voltage results in gradually increased lock problems, and at 5.25v no lock can be achieved.
BUT if I connect an active consumer level signal to my S/PDIF-4 Input A, then the Toslink lock on Input C can be achieved perfectly. This is at recommended voltages. The input on A can be from the same source or even a different source, as long as it is providing an active signal. It is as if the consumer signal 'helps' the Toslink signal to achieve lock. An interesting phenomenon indeed!
So, I was wondering whether you have been able to resolve your locking problem, and if so, how?
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