[cobaltmute]

So that implies no short on the output.
 
Have you tried to re-flow the joints on U6?

 

[Gotez]

getting the right voltages now, but is not seen by the pc yet. Should I anything else but plug it in?

 

[cobaltmute]

Just plug it in.
 
If you are using a Windows 7 machine, driver installation time can be long.
 
But to verify, you installed the resistors as posted earlier?

 

[Gotez]

Yes, they make a nice little tower.Is there a way to test the chips?
 
ah, the (3.3) point has no voltage. I will check around that area.
 
NEW: Device is found. I get the unidentified device message. Still no 3.3 on the (3.3) point. I get 5 volts on pin 1 of U1, and 3.7 on the opposite pin, but nothing on the 3.3 point. Does this mean that C7 is wrong?
 
 

 

[cobaltmute]

So you get output from the regulator, but nothing at the 3.3 point?  that is strange.
 
Check the resistance from 3.3 to ground. 
 
Also what to you get at the right side of L3 (the side away from the label) - both voltage, and resistance to ground?

 

[Gotez]

I resolderd a bit and now for both:
 
Voltage is 2v
 
Resistance is infinite.
 
My pc says: USB device not recognized.

 
 

 

[forsakenrider]

when I had the USB not recognized it was the i2s lines had a short. check them for resistance to ground.

 

[cobaltmute]

Quote:

I resolderd a bit and now for both:
 
Voltage is 2v
 
Resistance is infinite.
 
My pc says: USB device not recognized.

 
 

What is happening is that the 3.3V regulator is supply enough power to get the device recognized as being there, but the PCM2707 is not powered up properly.
 
2V is still to low.  Something is still the issue.  I would re-flow and check all your joints that are attached to the 3.3V lines.

 

[Gotez]

Quote:

What is happening is that the 3.3V regulator is supply enough power to get the device recognized as being there, but the PCM2707 is not powered up properly.
 
2V is still to low.  Something is still the issue.  I would re-flow and check all your joints that are attached to the 3.3V lines.

 
Been busy trying to find the short. Resistance is now 28k. Voltage is still 2. Device is still not recognized. I’m going to keep trying.
 
Could solder flux residue be the cause of this?
 
Anyway, thanks for all the help, I’ll post pics as soon as it works!!
 
 

 

[Gotez]

IT LIVES!!! I
 
After many hours of measuring and resoldering I found that the ground conncetion for U1 was not solder properly. After doing so it magically came alive.
 
Can’t comment on the sound yet, I have to listed some more first. I can say that is drives my IEM and senn HD121pro simultaneously a bit to easily and is very, very loud. It can make my ears bleed!
 
 
’ll post some pics soon.
 
 
And thanks for all the help!!!

 

[cobaltmute]

Glad to hear it works.
 
I've been surprised by the challenges that people are having as they all seem to be in the 3.3V section, which is essentially the same as the one for the grubDAC.

 

[mugdecoffee]

Just finished soldering mine together.  The build went well for the most part except I spent some time resoldering the PCM1794 over and over until some pin finally got soldered and sound came through the output.  While I've only listened to it a bit, its much much better driving headphones than my laptop or iPad.  I've tried it with my AKG K240s (600ohm) and Grado HF2s (32ohm) and it does a great job with both.  It has a clear sound with crisp highs and some solid, full bodied bass.  I don't have my amps with me at school so I can't compare it to anything decent but it sounds good.  Kudos to cobaltmute for the great design.

 

[Gotez]

As promised:
 

 

 

 

 

 

 

 
As you can see, photography is not my strong suit....
 
It drives my MS1 with ease, and sounds very fine. I'll listen some more for some in-depth review. My low end IEM buds do pick up a lot of static noise, could grounding the dac to a case help with this?

 

[cobaltmute]

I do not really endorse driving IEMs direct from the pupDAC.  You could be getting some issue with the current limits on the negative rail charge pump.

 

[mugdecoffee]

A couple suggestions I forgot to mention:
 
First, when resoldering the right side of the PCM1794 chip, I had a lot of trouble getting the pins with the capacitors in the way.  I'm not sure how critical the locations of C18 and C20 are but if they could be moved a little to the right, the pins would be much much more accessible.
 
Secondly, the caps for C24 and C26 on the BOM had leads that were a little too wide.  I had to force them in a bit which caused some of the through-plating to get scraped off and I was a little worried about shorting the pads to the ground plane.