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The GrubDAC - Page 70

post #1036 of 1046

Here is the picture:


post #1037 of 1046


post #1038 of 1046


As far as I can see, despite the soldering job, only pins 1, 2 and 3 on the PCM2706

seem to be problematic. The fact that it is recognized by the computer suggests

that the problem lies with either the I2S lines from the PCM to the WM8524, or

with the WM8524.


It looks like your soldering iron is too cold or there is not enough flux.

What kind of solder and soldering iron do you use?

post #1039 of 1046

I'm using a Hakko 936. I think it is the solder. I had thought it was flux core, but I think it's actually not, and I only had a "no clean" flux pen lying around that didn't seem to help a great deal. It's fine for through hole, but I guess surface mount stuff is a little more picky... I really should have waited and got some decent solder (it is also way too thick), but I was a little too eager to get going. I regret that now! Lesson learned.


I have re-flowed the WM8524, but still no go. I wonder if I may have fried it. Is there a way to determine that, short of just replacing it?


What kind of solder do folks recommend for this kind of work?


Thanks for the help.

Edited by iwuk78 - 3/30/14 at 1:30pm
post #1040 of 1046

This is the solder I's nothing special but it gives me good results:



I also use Solder Paste for SMD work.

I have my iron set for 500 - 550 F.


If you have access to an oscilloscope, you could check that the WM8524

is getting the correct signals, but short of that, replacing it is the next



Before you go to that extreme, do a continuity check.

Using the schematic, check that the pins on the PCM are

actually connected to the pins on the WM and aren't shorted

to anything else along the way. You can also check that

the other pins also go to where they should and are not

open or short.


Good luck!

post #1041 of 1046

Here is how the soldering job should look:


Sorry about the lint...

post #1042 of 1046

You got it! I checked continuity between the PCM and WM, which was fine. I then checked between the top of the pins on the WM and the pads and found one that was not soldered (looked like it was, even with magnifier). Beeped only when applying pressure. Resoldered it and BAM! Sound! 


Thank you for taking the time to look at this, it is much appreciated! 


I'm going to go and get ice cream to celebrate haha. 


Made my day :)


Thanks for the pics too. I think I'll definitely pick up some better solder before attempting any smd work again. The stuff I used needed the iron at about 600f to flow properly.

post #1043 of 1046
Originally Posted by iwuk78 View Post

Thank you for taking the time to look at this, it is much appreciated! 



Your welcome, I hope you enjoy it!

post #1044 of 1046
Hi Guys! Another one with a no-sound problem right here!

Here are some notes:

1. The GrubDAC is detected fine by Windows and shows up on playback devices. No instabilities.
2. The LED lights up.
3. 3.3V Test point shows stable ~3.29V.
4. 5V Across C5. 3.3V Across C1 & C15.

I've reflowed U1 and U3 and cleaned the board several times, with no luck.

Any ideas?

post #1045 of 1046


Can you check from ground to pin 2 on the wolfson?

There should be -3.3 volts.


As far as I can tell from the pictures, soldering looks good.

post #1046 of 1046
I managed to get it working smily_headphones1.gif

I didn't do anything special actually.
I just took it to take some high-magnification pictures using my USB Microscope, and then I checked for continuity across some of the Wolfson's pins, and then it started working.

It might be the multimeter leads that scrapped of some solder that bridged two pins. smily_headphones1.gif
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