Hi technical support team,
I've a small problem with the Digi+ using at a Raspberry B+.
Only the RCA coax output plug is playing audio.
The optical TOSLINK output is silent, no audio signal, but the LED is emmiting red light cont.
I changed the hifiberry with a second board (both brand new). But this give the same result.
I changed also the audio amplifier, only to be sure.... but no positive result.
Coax output is OK, but TOSLINK output doesn't work.
This was checked with both images, first the image that produce 1kHz tone for 10 minutes and also the Openelec XBMC player.
I'm curious what the problem can be.
Best regards,
Martin.
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11 comments
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HiFiBerry team Dear Martin,
you tested one Digi or two? If two boards show the same problem there is most likely an incompatibility with your DAC. Are you also sure that the optical cable is working correctly. As the red sender LED on the Digi turns on it is quite unlikely that is is a hardware problem of the Digi.
Can you try another cable or another DAC? Whyt DAC are you using?
Best regards
Daniel -
martin van beek Hi Daniel,
Thanks for the fast response.
Indeed I've tested 2 brand new received Digi+ boards with 2 different DAC's.
First DAC is the Naim Uniti.
Second DAC is the Harman Kardon BDS.
But can you explain me why it is quite unlikely that the TOSLINK won't work when the coax link is working fine.
Are these 2 signals connected together in parallel?
And is the datastream of the coax connecter the same as I will find on the TOSLINK LED.
In other words, do I measure the same signals when I observe both channels on an oscilloscope?
That is quit simple to check for me. Can you confirm this assumption?
And can you explain a bit the function of that small white micro pushbutton on the PCB.
Is there a white paper that explains all features and possibilities of this electrical circuit.
Best regards,
Martin. -
HiFiBerry team Dear Martin,
you're right, both outputs carry exactly the same signal.
The white pushbutton is only needed for a EEPROM upgrade. We will publish information about it when there is one available. The EEPROM identifies the board. In the future it should also allow automatic configuration of the board. However this functionality is not yet available in the Linux kernel.
Best regards
Daniel -
martin van beek Hey Daniel,
I've checked the electrical signals of the Wolfson chip and the electr./optical spdif outputs.
The electrical spdif signal is filtered and shows soft ramps, in both rising and falling directions.
But the optical spdif, the signal that goes to the TOSLINK optical module has a lot overshoot and undershoot.
There is no filtering at all. Ik measure a logical high level that is approx. 2.7Volt and above.
The logical low level goes from 0.9Volt down to zero.
So I have concerns about the logical high level signal, that will be arround 2.7Volt. Please can you send me the electrical datasheet of this optical device, or send at least the partnumber and brand of this device.
That should be great.
Can you also tell me what output is better, the optical or electrical interface, in respect with the phase jitter.
Or are they equal because there is some CRC calculation witin the data packages?
Best regards,
Martin. -
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martin van beek Hey Daniel,
On the pictures you can see both signals, the electrical and optical spdif.
Signal at channel 1 (top) is the data stream to the optical device.
Signal at channel 2 (bottom) is the data stream to the RCA output plug.
As you can see, the electrical spdif is filtered and has soft rising and falling ramps.
But the optical spdif has some distortion and is unfiltered.
Could the right extra decoupling capacitors around the U1, Wolfson wm8804 and optical device preserve this behavior.
I think about 1uF across pins 19 and 18, pins 7 and 8 etc.
What do you think about this?
Best regards,
Martin. -
HiFiBerry team The signal is ok as it looks. I suppose you did not terminate the output correctly, therefore the electrical outputs looks different. I guess, your optical cable has a problem if both Digi boards are not working with it.
Best regards
Daniel -
martin van beek Hi Daniel,
Indeed the previous cable was broken!!!
After buying a new TOSLINK cable, the Hifiberry was blasting me away ;o))
It sounds really perfect and I like the way the Raspberry interacts with the Hifiberry.
Thanks for your support, best regards,
Martin.
Ps I saw a lot of solder drops on the Hifiberry pcb, maybe you should improve the incomming good inspection at this point !!!
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