Technical help please! Optical Digital to Audio converter only working on one channel.

Hi All - would really appreciate some help troubleshooting this:

Have purchased two different (but applications-similar) DACs to get the optical digital out from my Vizio flatscreen (PCS formatted) into my Onkyo receiver (RCA) and speakers.

The problem I am having is that only the left RCA channel output of BOTH converters carries signal and the right channel is dead.

I have thoroughly troubleshot the receiver and the RCA cabling - they are not my issue. I thought the first DAC was faulty so replaced with a radio shack model and got exactly the same result.

As there is clear sound passing through the left channel, I don't think this is an optical cable issue. And though I am certain it *could* be a possibility, what are really the chances of this being two bad converters (with exactly the same 'problem'), from two separate manufacturers?

Sooo what am I missing and what would you tech-capable folks recommend I do to further troubleshoot the DAC, optical cable or TV end of things?

Very, very appreciated - I am frustrated,
Matt
Edited by Makakio - 1/11/13 at 10:22am

Thanks Glimme - I have tried swapping and it does indeed come out of the other speaker, hence you are correct and it is NOT my RCA cables nor my receiver.

Thanks also for the tech deets on the optical cable - nice to eliminate that as a possible source. So it's almost certainly the DAC or TV.

Could two DACs from different mfgrs really be bad?! What are the odds?!

Looking at the Vizio TV, I have the output set to PCM, so what else might I check there. Could it be as simple as speaker balance?!?!

Hi Arnyk - thanks for the feedback. I think we've eliminated the receiver and the RCA cabling as the problem by simply testing both cable and receiver LR channels on the working (left) channel of the DAC. I have also tested this on various inputs at the receiver, all with the same result. If the receiver had an optical digital input I wouldn't be messing with the DAC -- it is indeed a zillion years old in audiophile years (or about 10 actual years in fact - a brilliant Onkyo connected to Polk studio speakers that develop great sound (to my low-fi ears at least).

Thanks Arnyk - will go through t-shooting on the TV but was indeed wondering if the sound controls on the TV affect the optical signal output characteristics...

Hi all - just thought I'd loop back around and close out this thread.

So after both DACs not working I simply went to Radio shack and got a 3.5 male-to-RCA connector and used the headphones out on the back of the TV (which can be configured to static output via TV menu) and got fine sound. Certainly not optical quality or HDMI, but for my purposes works just fine.

I appreciate your inputs - best to you all.

Matt