GrubDac Help

Can you measure 3.3V when you stick a DMM probe in the 3.3V hole and the other probe on 0V?

I can't speak for the spot on the right, but the one on the left is a via (place where the trace goes vertical and is continued on the other side of the PCB).  By itself, it's not going to hurt if you get solder there, but it depends on what else it's touching.

Just a hint, but you might try cleaning the PCB of all that flux, too.  The pads and pins on some of those parts are small enough to short if there's enough dirt mixed in that flux.

Cobaltmute will probably have some more ideas if those don't improve things.

So, I just built one of these today, so, I am far from an expert, yet, it worked, so, that gives me some props... ;-)

Your part placement looks good in terms of orientation, I need to check values.

My big suspicion is the 2706. You have a LOT of solder on those pins. Remember, just a dab will do ya!  I would go back and heat those joints and try to remove some of the excess solder. I see some potential bridges on a couple of pins. DId you do the "back light" trick on the grubdac site?

   http://www.diyforums.org/GrubDAC/GrubDACphoto-build-1.php

It REALLY works good. I was able to clear a bridge using this technique. The board is really well designed for this type of examination.

BTW, you need to clean your board better. Go to the pharmacy and get some 91% rubbing alcohol and a cheap-a-- nylon toothbrush and scrub hard! makes all the difference!

Hope this helps.

Well, if the 3.3V test point won't work, that often points out that the problem is with the TPS chip on the back (U2).  We can't see it very well from the photos you've supplied so far.  Can you clean that chip up and see if there are any solder bridges/cold solder/no solder etc.?

Edit: Actually, from that last photo the PCM and WM chips look relatively OK.

Can you give us a better picture of U2? Something straight on? Hard to tell from the initial pic.

Thanks

No power on the 3V3 point means that the regulator has shutdown, likely due to over-current shutdown due to a bridge.

Looking at the back-lit version of the board I see two possible bridges on the PCM

the left one on the pic looks visible on the other pic of the top side as well.  That one will cause a bridge to shut to board down as it is from a power pin to the ground plane.  The one on the right will cause problems as it is on the data lines to the WM8524.

BTW, Did you clean up that bridge between C9 and U3?

That's great news Lanning.

Enjoy your DAC!