pupDAC Step-by-Step Build Thread

[holland]

Quote:

SO WHAT SHOULD I DO???

 
Put some flux on it.  A hot iron, and wipe it, parallel to the pins, away from the chip.  It'll flow onto the pads.  Clean the iron and wipe again.  The excess should stick to the iron in bits and get cleaned off with each swipe.  Braid if you need to, as in there is lots of solder.
 
I use a flat tip, not pointy, for this, to heat up 2 pins.  I use the same method to break bridges.

 

[tomb]

Yes - what they said.  Either a judicious use of the de-soldering braid, or wipe "down and away" with the soldering iron tip horizontal to the pins.  You must be sure the soldering iron tip is clean of any solder, or it will make the situation worse.
 
I've been known to use a toothpick (with the solder melted), dental pick or even an X-acto knife to cut through a bridge.  The X-acto knife is a last resort, though, because it can easily cut through the ground plane and traces.  You could end up doing more damage than fixing it.  Try the stuff mentioned above first, before you do anything else.  It shouldn't be a big deal at the point you are at right now.

 

[COOKIESnPIE]

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[tomb]

Quote:

Did it with flux... no desoldering braid needed. Thx
 

Great!

 

[mvrk10256]

So just finished building and guess what. Unrecognized. I checked all the pins,a nd I have built a few grubs now, so I am pretty sure all is right. Help me out here guys. 
 
Starting with the top left corner (where LED is) here are the voltage vias
Rated Voltage  -----  My voltage
3.3V                         3.302V (next to U4)
3.3V                         2.204V( next to r10)
5.0V                         5.006V (under U5)
-5.0V                        -5.004V (next to u7)
2.5V                         2.497V ( next to L4)
4.5V                        4.701V (above C6)
-2.5V                     -2.501V( under L6)
 
Whats wrong with it? I reflowed everything I could think of, LED is on. 
 
It seems that U2 is pushing 2.2V instead of 3.3. I have tried reflowing it. It is getting 5V input. It seems to be the correct part. Maybe I got shipped a bad VR?

 

[mvrk10256]

Update: It was the LDO, removed it, jumped 3.3V to the location, works like a charm.Just super annoyed cause that LDO is gonna cost me like $8 including delivery. 

 

[tomb]

  Update: It was the LDO, removed it, jumped 3.3V to the location, works like a charm.Just super annoyed cause that LDO is gonna cost me like $8 including delivery.

 
Shoot me a PM and I'll send you another one.  I need to know who you are and your address.  I can look up customers one at a time to see who is from Austin, but that might take me a while. 

 

[adnc]

I ordered a board and build pupDAC with the parts I had. I'm impressed how good the sound quality is. There is a slight distortion I think I hear when no audio is on the board. on headphone aswell as on chinch. Also this is not hearable everytime. Does anyone else know this problem? Voltage measurements are all fine.

I'm running it on a raspberry pi and the above problem also occurse on my notebook.

I use pupdac to output my mpd music, but I'm only able to use software driven volume. What about hardware volume controll with pupdac is this possible?

 

[mvrk10256]

@adnc - are you driving headphones directly from the DAC? This is not a good idea, you really need to feed the signal into an amp.
 
@TomB  - you guys ever plan on doing a phono preamp?

 

[tomb]

I ordered a board and build pupDAC with the parts I had. I'm impressed how good the sound quality is. There is a slight distortion I think I hear when no audio is on the board. on headphone aswell as on chinch. Also this is not hearable everytime. Does anyone else know this problem? Voltage measurements are all fine.

I'm running it on a raspberry pi and the above problem also occurse on my notebook.

I use pupdac to output my mpd music, but I'm only able to use software driven volume. What about hardware volume controll with pupdac is this possible?

 
The pupDAC is not really designed to directly feed headphones.  If the headphones or earbuds are very efficient, then you may get pretty good results.
 
The sound that you're hearing could be one of two or three things: 1) clipping while trying to power headphones, 2) the raspberry pi, or a grounding issue on the PCB.  I have seen a few threads and comments that indicate perhaps the raspberry pi is not quite up to streaming high-quality audio.  Further, the pupDAC has more than a trivial current drain relative to USB from a laptop.  (Maybe the raspberry pi has even less power capability, but I dont' know.) A few posts back in this thread, I recommended a powered-USB hub unless you are feeding it from a full size desktop that can handle multiple USB power feeds.  As for the ground, this can cause some really irritating and intermittent noise issues.  It's one of the reasons that all Beezar DACs use dual ground wires/connections on the output connections.*  Without an excellent solder joint, t's very easy to get a poor connection on only one single ground wire with the size of PCB pads that are involved.
 
Lastly, hardware volume control is sort of self-evident: there is no stereo volume pot on the pupDAC PCB.  The pupDAC would be about twice as big if a quality stereo volume pot was included - that was not in the design criteria.  However, there's nothing to stop you from wiring a pot externally to the pupDAC outputs.  I think an amp would be better, though.
 
* If you're connecting into the 3.5mm stereo output jack, it only has one pin connected to ground.  Try to make certain that the ground connection has a good solder joint.

 

[tomb]

  @adnc - are you driving headphones directly from the DAC? This is not a good idea, you really need to feed the signal into an amp.
 
@TomB  - you guys ever plan on doing a phono preamp?

 
It's been discussed with both Dsavitsk and cobaltmute from time to time, but there's nothing so far.

 

[mvrk10256]

So I think we should give TomB a round of applause. Once I sent him my addy, he mailed me the part that was DOA in the original kit immediately. Got it in today, soldered it down, and boom. Everything works perfectly. 
 
Now I just need to find time between classes and all these damn interviews to finish the enclosure. 

 

[tomb]

  So I think we should give TomB a round of applause. Once I sent him my addy, he mailed me the part that was DOA in the original kit immediately. Got it in today, soldered it down, and boom. Everything works perfectly.
 
Now I just need to find time between classes and all these damn interviews to finish the enclosure.

 
Many thanks!  Glad you got it working - enjoy!

 

[mvrk10256]

   
Many thanks!  Glad you got it working - enjoy!

 
Thanks, I will post some more good build/assembly/review stuff later. 

 

[COOKIESnPIE]

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