[kchapdaily]

i finished building a grubdac kit yesterday. plugged it in to my desktop, windows recognized it and installed drivers. foobar also recognized it. plugged it into my starving student, and i just get heavy distortion/static when nothing is playing. when a song is playing it sounds really distorted, lots of static, and kind of like its under water. i checked for bridges, dont really see any. theres one spot that looks like a possible bridge with a backlight. but i think i cleared it. melted the corner of my box cap a bit trying to fix that bridge, but this was after i already discovered it wasnt working right. do you guys see any other problems?
 
 
 

 

 

 

[tomb]

There does appear to be a bridge between the 2nd and 3rd pins on the right side of the PCM2706/7 in your last pic.  You might try simply clearing it with an X-acto knife.  I don't see any on the DAC chip.
 
One other thing - and I would suspect this first, given your description - a bad ground connection on the signal output wires can cause huge static and distortion, especially if the ground is intermittently connecting.  That first pic is a little blurry in that area, so I can't tell whether you've got some cold solder joints there.  You would need to check your connections on the output connector(s), too - depending on whatever you're using.

 

[kchapdaily]

thanks for the quick reply. i will attempt to clear that bridge again. i will also check my output signal grounds. i hope that the problem is in the grounding, because ive been trying to make sure those 2 pins arent shorted for a long time now 

. once i get back to my desk ill post my results.

 

[tomb]

Quote:

thanks for the quick reply. i will attempt to clear that bridge again. i will also check my output signal grounds. i hope that the problem is in the grounding, because ive been trying to make sure those 2 pins arent shorted for a long time now 

. once i get back to my desk ill post my results.

Just another thought - but it appears that you've used the same wire for OL and one of the G's.  Is it possible you're getting these mixed up at the connectors and assuming the two like wires are both Ground?

 

[kchapdaily]

thats my fault- i wasnt paying full attention when i picked the wires for the rca leads. i used the red and white wires for the right lead, leaving me the two identical wires, which were supposed to both be ground, for the left lead. 
 
UPDATE: ive reflowed the joints on the ground signal out leads, dont think that was the problem. im also almost positive there is a bridge between the second and third pads where the PCM2706/7 is attached. its definitely not a bridge between the pins, as i cannot reach it with the tip of my soldering iron or an exacto. its also fairly smaller now than it is in the original image. im going to have to get a very fine pin and try and clear it tomorrow. hopefully that works, otherwise i guess ill have to desolder the whole chip to get at it. also there might be a bridge between the bottom left most two pins

 

[kchapdaily]

i cleared all the bridges on the PCM chip, and upon further inspection there was a bridge on the dac chip. cleared that, and now it works. sounds great! even though it was a little rough to get working, im quite happy with it. not going to be doing anther surface mount build anytime soon though.

 

[tomb]

Quote:

i cleared all the bridges on the PCM chip, and upon further inspection there was a bridge on the dac chip. cleared that, and now it works. sounds great! even though it was a little rough to get working, im quite happy with it. not going to be doing anther surface mount build anytime soon though.

Glad to hear you got it working!

 

[doulos24]

i cleared all the bridges on the PCM chip, and upon further inspection there was a bridge on the dac chip. cleared that, and now it works. sounds great! even though it was a little rough to get working, im quite happy with it. not going to be doing anther surface mount build anytime soon though.

oh don't give up glad you got your board working but a little investment in the proper tools makes smd a breeze. Next time try using a flux pen and some very thin solder on a chizzle tip makes it very easy to avoid solder bridges and to pull them out with a small piece of solder wick. 

 

[kchapdaily]

thanks for the advice. im at college right now and i didnt bring all my stuff with me. forgot my desoldering braid and my flux but at least its working.
quick question though. does anyone install an on off switch? when i put my desktop to sleep the grubdac stays on. shouldnt really damage it though, guess im just used to shutting stuff off.

 

[tomb]

Quote:

thanks for the advice. im at college right now and i didnt bring all my stuff with me. forgot my desoldering braid and my flux but at least its working.
quick question though. does anyone install an on off switch? when i put my desktop to sleep the grubdac stays on. shouldnt really damage it though, guess im just used to shutting stuff off.

It's technically not on - just like the PC, if there is no USB communication, then there is no activity with the chips.  However, even if the PC is asleep, there is still 5V from the USB buss, so the grubDAC's LED stays lit.
 
It won't harm a thing and you can leave it connected for days, weeks, months, ...

 

[kchapdaily]

awesome that's definitely good. i kind of thought that was the case, but better safe than sorry.