Grubdac doesn't work. Please help.

What is the voltage of the 3.3V testpoint with respect to 0V. Check the soldering on your 3.3V regulator. Can you provide some pictures?

I had a similiar problem.  I reflowed the solder on U1 and got mine working.

The first check, as mentioned is to check to see if there is 3.3v at the 3V3 point.  You would check with your multimeter from 3V3 to either end of L2 (as your 0V point will have a wire in it with the cable dac).

I suspect that you will have 0V there indicating a bridge on one of the parts.  You will then need to examine the board very closely for bridges.  The most common place is on the PCM2706.  Use the hint of holding it up in front of a light and seeing if there is anything that looks like it is crossing two pins.  Another bridge to watch out for is if there is solder from a pad to the top of the clock (X1).

And post pics if you can, there is a lot of eyes that will look at your board and may be able to spot something. 

Quote:

Originally Posted by acvtre 

So the C5 is the big capacitor, right? So now I'm wondering why Tomb sent me a smd capacitor and called it C5. However, I have no voltage on 3.3V.

This was posted in the GrubDAC thread.  It's an extra that was a mistake in the BOM.  I'm not going to worry about re-packing ~100 kits for the few pennies' worth of an SMD capacitor, though.

 

Quote:

Originally Posted by acvtre 

2)I soldered the smd capacitor without taking care of the position, is it right? is it possibile to solder them upside down?

 

Do you need some specific pictures or just a general one of the two sides?

No, there is not "top" and "bottom". Only side-to-side orientation.

General picture of each side, use the best lighting possible with the best focus possible.

 

Quote:

Originally Posted by acvtre 

ok, so everything it's fine but I have no voltage on the 3V3. So what should I do?

The 3.3V is controlled by the TPS regulator on the back side.  That could indicate a problem with how the TPS chip is installed.  Or, it could mean something else is shorted/disconnected to the extent that the TPS regulator can't operate.

We still need those pics.  Either you have a part in the wrong place, or some pins are bridged somewhere.  That's pretty much the cause of every problem.  So more eyes are needed to help you figure it out.  I'm certain we'll be able to help you fix it with good pics, though.

P.S. Just an FYI for future reference, but I suspect cobaltmute (the Expert) is subscribed to the GrubDAC thread, but probably not to this one.  So unless he has time to scan the general threads, he may not see your latest posts.  That's kind of why most of like to keep posts in the threads where they belong. If he doesn't see this eventually (I know he posted up there once), I'll let him know ... but we could still use those pics.
 

No voltage at 3V3 means either that the regulator is not installed properly or there is a short on the pins somewhere.

Good picture of the topside will help.  Usual places to look for a bridge is between the pins on the PCM2706 and WM8524, as well as from the pads to the top of clock (X1).  There is very little that you can bridge on the bottom (unless you bridge the pins on the regulator itself).

You can hold the board up to a light, and look for lines between the pins on the PCM2706 (where most people bridge).  You should be able to see the difference between a line that is on the board and one that is a bridge. An example of a good clean board in front of a light is here:

http://www.head-fi.org/forum/thread/445155/the-grubdac/435#post_6805303

From what I can make out from the pictures:

- It looks like there may be solder from a pad to the top of X1.  Use some solder wick and ensure that is not the case.

- R1 looks to have a big blob of solder around it.  Again, clean it up with solder wick.