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The GrubDAC
Dec 29, 2010 at 3:05 PM Post #616 of 1,079
I have seen the same kind of issue with a different DAC I built.  Turning the amp off would shut the DAC down, but it is not a reliable occourance so it makes it difficult to determine what exactly is happening.  I'm wondering if it is a ground bounce or something similar.
 
Dec 29, 2010 at 3:27 PM Post #617 of 1,079
Oops. I could have sworn I replied to this thread yesterday.
 
Quote:
nullstring said:
Quote:
bobsayshi said:
Hi guys, I have a semi-related problem that is troubling me. Every time I turn on my lamp that is on the same power strip as my computer my DAC stops working (it freezes or something). Would buying a better power strip fix this? I have a generic "Staples" brand power strip.
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Have you tried moving the lamp off of the power strip (but still on the same circuit) and seeing if it fixes it?
 
If thats the case, I would suppose a better power strip would fix it. (but that'd be pretty weird)
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I just looked, and the lamp isn't on the same power strip. I have two strips plugged into the wall. One strip has my computer, amp and telephone. The other has my monitor, soldering iron (it's home is on my desk), my cell phone charger, and my lamp.
 
Also, the DAC only stops when I turn the lamp off, not on, like I said earlier.
 
Dec 29, 2010 at 3:49 PM Post #618 of 1,079
Likely magnetic/radio interference. My GrubDAC freezes when my UPS activates due to mains fluctuation. Also happens if there's some intense lightning. My lamp has the twist switch, maybe that's more gentler compared to the rocker type.
 
Dec 30, 2010 at 9:46 PM Post #619 of 1,079

 
Quote:
bobsayshi said:
Oops. I could have sworn I replied to this thread yesterday

I just looked, and the lamp isn't on the same power strip. I have two strips plugged into the wall. One strip has my computer, amp and telephone. The other has my monitor, soldering iron (it's home is on my desk), my cell phone charger, and my lamp.
 
Also, the DAC only stops when I turn the lamp off, not on, like I said earlier.
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  I'm guessing it's an inductive spike being coupled into either the audio or USB cable.  Try unhooking the audio cable, switching off the lamp, then plugging the audio cable back in.   If it's still working then it's the audio cable. If not, I'd suspect the USB cable.  (It may also be a power-line spike coming from the ballast in the lamp (florescent?) getting into the audio cable via the audio gear is connected to it.)
  I'd be surprised if a power line spike was making it through the PC power supply and the DAC power supply chip.  Is the computer a laptop?  If so have you tried to see if the problem occurs on battery power?
 
   If it looks like the USB or audio cable try a snap on choke, as Avro suggested.  For best results use the open core type (looks like an open rectangle for the snap on style or just a circle for the pull-through types) that you wind several turns of the cable through vs. the ones that just snap around the outside of the cable.  (Follow the directions on the package exactly for winding the cable - the direction of the turns is important if you wind on both sides of the rectangular types.)
 
Good hunting!
  Bob
 
Dec 30, 2010 at 10:07 PM Post #620 of 1,079


Quote:
bobva said:
But I'm thinking about bringing the output of the DAC out to a jack on the back of the headphone amp I'm building, then patching back into an input, so I can use the DAC as a standalone item if I need to.  Getting the level down a bit might still be a good idea.

 
Regards,
   Bob
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That worked out pretty well.  I used 1k / 15 turn pots on the output channels.  After fiddling with them for a bit (0 db?  +4 db?) I just punted - I connected the line out of my iPod to an analog input of my (just finished!) amp and my computer to the USB/DAC input, both playing the same song. Then I adjusted the DAC output pads until I couldn't tell any significant volume difference between the two, and then equalized the two DAC channels with the scope.
 
GrubDAC -> Millet Max -> RS2 or D5000 sounds great.  Millet also does a fantastic job with my hard-to-drive Senn HD-580's
 
Jan 1, 2011 at 6:05 PM Post #621 of 1,079
I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
 
Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
 
Bad U1 maybe?
 
Jan 1, 2011 at 6:23 PM Post #622 of 1,079
Do you have access to a multimeter to make some measurements?

A picture with as much light and focus as you can muster of the top and bottom of the board would also be helpful.
 
Jan 1, 2011 at 9:04 PM Post #623 of 1,079


Quote:
csholtmeier said:
I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
 
Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
 
Bad U1 maybe?
Click to expand...


I apologize for not activating your account - it's done now.  Because of previous abuse, I run a "whois" on the IP address of an account request.  If the "whois" gets blocked (yours did) or if the trace log bounces to some domains that I know are abusive, I do not activate the account.  While a blocked whois is not necessarily a spam indication by itself, the uncertainty was enough to make me suspicious without additional info.  Again, my apologies.
As for your GrubDAC - what jdkJake said.  
smily_headphones1.gif

 
Jan 2, 2011 at 8:31 AM Post #624 of 1,079


Quote:
csholtmeier said:
I'm having a probelm with my GrubDAC build, and am tired of waiting for my DIYForums account to be activated.
 
Initially the unit did not ouput sound. It would be recognized by the PC, no output. I reflowed U1, and subsequently got output from the unit for about 30 seconds. Then same situation. Reflowed U1 again, this time it only worked long enough for the Windows recognition tone to play.
 
Bad U1 maybe?
Click to expand...


Is your board clean?  And as the others said, you can check the 3V3 point for voltage when the board stops working.
 
Jan 8, 2011 at 11:31 AM Post #627 of 1,079
Have you verified 3.3VDC at the test point?

There is still quite a bit of flux on the board, particularly the bottom. Suggest you use 91% alcohol (available at any drug store) and a nylon toothbrush to scrub it off.
 
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