People with monoprice COAX-optical converters - beware!

[linuxworks]

the next thing I would do in debugging this is to see if the power supply is stable at both times: the cold boot 'bug mode' and the reboot 'good mode'. do you see something close to +5v off the regulator chip's output at both times?

this might take some work to see. I would temp-solder (tack solder) a wire from the regulator output and clip my DVM or scope lead to that and watch it.

another guess might be extra bypassing or better quality bypassing (Vcc to ground, near the main IC). they do have a bypass cap there (ceramic) but maybe its just not working well? that's a long-shot, though.

I've been using my modified monoprice unit for weeks, now; but the version I have does not have a dead short in series with the opto block - mine uses a parallel R which is 'close to zero' but not truly zero. I doubt that would matter - but maybe try breaking the wire on the top and putting an R in there (or a trimmer pot) and varying it to see if that matters at all in your case.

and also, mine is INSIDE the pch box. that means I draw power from the +5v supply (meant for the hard drive) and I entirely bypassed my internal 7805 regulator. I think I have a good strong +5v this way and so that's also a difference between your setup and mine.

[psobot]

Hmm... I'm not sure which pins to be probing, but off of two of the regulator's 3 outputs, I'm getting +3.82v, and if I probe the other pins... I get +8.42v. Should I try your mod - attach it to the PCH's output?

[psobot]

Wait - I'm pretty much sure of it now. If I short out the pins with my multimeter, then yes, I get +8v, but the pins that go directly to the opto emitter from the regulator - the main power source, only carry +3.8v! A difference of -1.2v should be more than enough to cause this problem. I'm going to do the mod... I was about to return the PCH for all the trouble it's caused me, but no, I'd rather try one last time to get it to work.

[psobot]

Yeah... forget it. Didn't work, at least not well. I don't care if it's my receiver that's not working properly, or the Monoprice box - but it worked terribly.

I'm returning my PCH tomorrow morning - too much hassle, way too many bugs, terrible interface, and although it plays the files I want... it looks and works like crap. There's a slim chance that I'll get an A-110 if it ever comes out. Thanks for the help, linuxworks.

[linuxworks]

it should be interesting to see if others (with this new 'wire shorted' monoprice converter) are having problems or if things are getting better. if you have a monoprice unit and you don't mind opening it up, post your results here and whether you have the resistor version or the wire-short (new) version.

[jus10case]

(08-06-2008 04:27 PM)linuxworks Wrote:  it should be interesting to see if others (with this new 'wire shorted' monoprice converter) are having problems or if things are getting better. if you have a monoprice unit and you don't mind opening it up, post your results here and whether you have the resistor version or the wire-short (new) version.

So did anyone ever figure out if this box works? I was going to get one to go from coax to optical to hook up to my surround sound as it only has an optical connection. Thanks.

[syam]

If by "this" you mean a monoprice converter, it works for me just fine. With the April firmware (and with the next one, when they will remove the newly introduced bug called "SPDIF off after playback"), it worked fine without any modifications (soldering). I did some soldering only to be able to use the current, June firmware. I used the linuxworks' approach (soldered in one additional resistor, 100 Ohm), and it works perfectly.

[jus10case]

(08-19-2008 03:06 PM)syam Wrote:  If by "this" you mean a monoprice converter, it works for me just fine. With the April firmware (and with the next one, when they will remove the newly introduced bug called "SPDIF off after playback"), it worked fine without any modifications (soldering). I did some soldering only to be able to use the current, June firmware. I used the linuxworks' approach (soldered in one additional resistor, 100 Ohm), and it works perfectly.

yes the monoprice, and thanks for the reply!

[Nikkele]

I've tried the mod as well mine (which i recieved today) had a 330ohm resistor instead of the 270ohm.
I've shorted this resistor, the light did became al little brighter but still i don't have any audio even after power cycling the convertor.
I'm not sure what to do now, before a wll buy a more expensive converot i first want to be sure that the S/PDIF output on my PCH actually works. If I know the output works I will buy the more expensive one, is there a wat to test if the S/PDIF output works at all? I don't have a device that accepts the Coaxial-in?

[linuxworks]

(10-14-2008 09:14 PM)Nikkele Wrote:  I've tried the mod as well mine (which i recieved today) had a 330ohm resistor instead of the 270ohm.
I've shorted this resistor, the light did became al little brighter but still i don't have any audio even after power cycling the convertor.
I'm not sure what to do now, before a wll buy a more expensive converot i first want to be sure that the S/PDIF output on my PCH actually works. If I know the output works I will buy the more expensive one, is there a wat to test if the S/PDIF output works at all? I don't have a device that accepts the Coaxial-in?

I'm replying late but better late than never?

the only things that come to mind to help debug are other 'known working' spdif receivers.

lots of things could do that - soundcards often have opto and coax inputs. most have outputs but some do have digital inputs.

the digital signal isn't something you can really easily see if its 'working' or not but having a device that knows the protocol and gives a light saying 'data ok' is what you need.

a DAC (digital to analog converter) also gives a 'lock on' led and they almost always have both a coax and opto input. you can find new dacs and even used ones on fleabay. pro audio stores (music stores) will also have affordable DACs that musicians and audio recording guys use.

the monoprice units are somewhat cheap (...) and there are better units out there. I think part of the problem is the low quality toslink opto block (part) they use. I was not impressed by it and it may be the heart of the whole problem.

if you are ok with DIY, you could swap out that 'low end' toslink sender for a better one, such as found at digikey.com and other places. I think its a simple 5v standard (not 3.3) and so if you find a toslink sender (totx series) it might just do the trick. I do NOT like the quality of the opto block monoprice uses.. it works for some but not all.