troubleshooting opus dac

Jan 21, 2014 at 6:29 PM Thread Starter Post #1 of 9

kugino

Headphoneus Supremus
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i took out my opus dac and fired her up again and for some reason, am not getting any sound via the optical connection. usb works fine, but once i switch to toslink, no sound. my imac recognizes the toslink. but on the receiver module, only one of the led lights is green. the others are red. i'm guessing that it's not detecting the optical signal, but i can't figure out where in the chain the problem is.
 
this opus dac was built for me a while back and i guess i've only used it via the usb but thought i'd try the optical, only to find that it's not working. i'm using the older v. 1.0 dac board. and the v 1.1 receiver module.
 
the connections go like this:
 
usb -> I2S -> OTTO -> metronome -> DAC/ballsie -> SE and balanced outputs
 
toslink/coax -> SPDIF ->receiver -> metronome -> DAC/ballsie -> SE and balanced outputs
 
i've tested the security of the connections and they're all fine. i've not tested the electrical connections w/ a multimeter yet. that's next...
 
the question is, USB input works fine, but when i switch to toslink, there is no sound. so, where in the chain should i check? i'm assuming the toslink connector and the receiver are the first culprits, right? 
 
all the dip switches are per the recommended stereo configurations given by twisted pear. any suggestions would be welcome.  thanks.
 
the receiver module. only the non-audio LED is green. others are red.

 

 

 

 

 

 

 

 

 
Jan 21, 2014 at 8:14 PM Post #2 of 9
What's the DC voltage reading between the "VCC" and "G" terminals on the TORX module?
 
Here's the link to the PCB layout image:
 
 
http://www.twistedpearaudio.com/images/digital/torx_layout.jpg
 
Jan 22, 2014 at 12:41 AM Post #3 of 9
hi marshall.  i'm using a crappy multimeter b/c my good one has a dead battery. i think it's reading 8V. if that sounds way off let me know...but i think that's right.  any thoughts?
 
Jan 22, 2014 at 1:51 AM Post #4 of 9
8 volts is a little higher then I expected there but it's OK.
Sounds like it would be good idea to check and re-adjust (if needed) the PSU voltages when you get the new batteries in your good meter. Anyhow...
What's the DC voltage reading between the lead sticking out of the top of L1 and ground?
(should be 3.3 volts)
 
Jan 22, 2014 at 2:33 PM Post #5 of 9
hi marshall,
 
got the battery replaced. between VCC and G, i get 7.56V
 
between L1 and G is 0. replace the module?
 
i suppose i should check to see that the coax input is working, too, which might rule out issues at the receiver, etc. first, gotta find something that has a coax output...maybe an old dvd/cd player. i'll let you know what i find out.  thanks.
 
Jan 23, 2014 at 7:01 PM Post #6 of 9
update: coax input works fine. receiver LEDs all light up green. so it's the torx module. i'll order a replacement. 
 
Jan 23, 2014 at 7:24 PM Post #9 of 9
  You could just drop the optical module in the mail and I will fix it....
(kinda sounds like the ¢75 regulator is kaput)

haha...i just ordered one before i saw this. let me try and contact TP and see if i can cancel that order and if so, i'll mail the module to you. thanks.
 

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