[tomb]

Depends on what you define as a bridge. I was not referring to the ground "relieved" connection on that single corner pin, but to the apparrent solder bridge to the pin at its left.

 

[Avro_Arrow]

I don't know at what point in the troubleshooting the pictures were taken, but
I looked at them very closely at their original resolution and I didn't find
any "unintended" connections. The connection from C9 (?) to the Wolfson
looks to be on its last legs and my need repair, but otherwise I think the
soldering job should work. The PCM may be fried by earlier mistakes though.
 
Just my Nickel (Canada doesn't have the penny any more...).

 

[tomb]

Quote:

I don't know at what point in the troubleshooting the pictures were taken, but
I looked at them very closely at their original resolution and I didn't find
any "unintended" connections. The connection from C9 (?) to the Wolfson
looks to be on its last legs and my need repair, but otherwise I think the
soldering job should work. The PCM may be fried by earlier mistakes though.
 
Just my Nickel (Canada doesn't have the penny any more...).

OK - I've been looking at it all this time from my phone and I guess the display left a lot to be desired.  I can see now that I was mixed up (but not about only two bridged pins on the PCB design).  Thanks for correcting me.
 
I agree if there are no bridges, then the PCM is probably fried.

 

[Caretaker007]

Quote:

I don't know at what point in the troubleshooting the pictures were taken, but
I looked at them very closely at their original resolution and I didn't find
any "unintended" connections. The connection from C9 (?) to the Wolfson
looks to be on its last legs and my need repair, but otherwise I think the
soldering job should work. The PCM may be fried by earlier mistakes though.
 
Just my Nickel (Canada doesn't have the penny any more...).

 
The connection from the C9 to the Wolfson looks weird in the photo but I believe I reflowed those pins anyways after the photo was taken.  The continuity tests out fine. 
 
Quote:

OK - I've been looking at it all this time from my phone and I guess the display left a lot to be desired.  I can see now that I was mixed up (but not about only two bridged pins on the PCB design).  Thanks for correcting me.
 
I agree if there are no bridges, then the PCM is probably fried.

 
That's what I figured. I just ordered a new PCM.  Hopefully that was the only chip damaged.  
 
I will report back when it gets in and I have time to repair it.  Hopefully it will be good news. 

 

[Caretaker007]

Got the PCM2707 in.  Replaced it.  Triple checked for bridges, both visually and continuity testing. Tested the continuity from the pins to the trace points. Everything looked and tested perfect.
 
After plugging in, I first noticed the LED flickering and then the regulator was getting very hot.  Unplugged.  Traced and checked ALL of the components for shorts...twice. Nothing.
 
Plugged back in check the voltages. Before I could start measuring, smoke starts coming from the PCM chip. Fried again!!! 

 
 
A bunch of the pins are grounded now on the PCM that were definitely not before so definitely fried.  I have another PCM (was intended for a PupDAC build) but I don't trust the board at this point and removing this PCM this time has wrecked the anchor points. 
 
I refuse to give up and I going to order a new board from Beezer (along with a PupDAC PCB, future project) and I am going to place a reorder for the components at mouser. One problem is that the Crystek Oscillator is no longer stocked at Mouser.  Can someone suggest a alternative or maybe Tom has one he can sell to me and add to my PCB order when I place it?

 

[tomb]

Quote:

Got the PCM2707 in.  Replaced it.  Triple checked for bridges, both visually and continuity testing. Tested the continuity from the pins to the trace points. Everything looked and tested perfect.
 
After plugging in, I first noticed the LED flickering and then the regulator was getting very hot.  Unplugged.  Traced and checked ALL of the components for shorts...twice. Nothing.
 
Plugged back in check the voltages. Before I could start measuring, smoke starts coming from the PCM chip. Fried again!!! 

 
 
A bunch of the pins are grounded now on the PCM that were definitely not before so definitely fried.  I have another PCM (was intended for a PupDAC build) but I don't trust the board at this point and removing this PCM this time has wrecked the anchor points. 
 
I refuse to give up and I going to order a new board from Beezer (along with a PupDAC PCB, future project) and I am going to place a reorder for the components at mouser. One problem is that the Crystek Oscillator is no longer stocked at Mouser.  Can someone suggest a alternative or maybe Tom has one he can sell to me and add to my PCB order when I place it?

I am sorry to hear this.
 
Send me a PM and I'll shoot you a new grubDAC PCB.  If there's any chance it was the PCB, I'd rather just give you another one.  I probably have a crystal, too, although the one we changed to on the pupDAC is OK for the grubDAC, too:
C3391-12.000
 
Just an FYI, but all the pupDAC PCB's are electrically tested. 

 

[mawoca]

Another GrubDAC is alive and well in this world! Aside from a couple of issues that were resolved very quickly by reading through this thread, the build went fast and was a ton of fun! And of course the sound is the ultimate reward, as this blows my little ELE EL-D01 away. Right now I have it paired up with a buffered-ground CMoy (with an OPA2107 in it) and my trusty SR60i's. I had no idea you could get sound like this out of the SR60s, lol. So good! My thanks to Cobaltmute and TomB and everyone who has built one before me for sharing their experiences.

I'm very excited to start building my Pimeta V2 now and finding matching cases for that and the GrubDAC!

 

[tomb]

Quote:

Another GrubDAC is alive and well in this world! Aside from a couple of issues that were resolved very quickly by reading through this thread, the build went fast and was a ton of fun! And of course the sound is the ultimate reward, as this blows my little ELE EL-D01 away. Right now I have it paired up with a buffered-ground CMoy (with an OPA2107 in it) and my trusty SR60i's. I had no idea you could get sound like this out of the SR60s, lol. So good! My thanks to Cobaltmute and TomB and everyone who has built one before me for sharing their experiences.

I'm very excited to start building my Pimeta V2 now and finding matching cases for that and the GrubDAC!

Thanks!  Glad to hear you like it and that everything worked out!

 

[acvtre]

Hi folks, I've just resoldered the main chips: U1, U3 and another couple because time ago I burned them accidentaly with the multimeter while the dac was on.
Now the dac got immediately recognized by the pc when I plug in the usb, but I can hear no sound, not even a hiss/buzz from the speakers? 
 
What should I check?

 

[tomb]

Quote:

Hi folks, I've just resoldered the main chips: U1, U3 and another couple because time ago I burned them accidentaly with the multimeter while the dac was on.
Now the dac got immediately recognized by the pc when I plug in the usb, but I can hear no sound, not even a hiss/buzz from the speakers? 
 
What should I check?

You need to check U3 - that's the Wolfson DAC chip and it governs everything about the analog output.

 

[acvtre]

Quote:

You need to check U3 - that's the Wolfson DAC chip and it governs everything about the analog output.

Ok, this means that the U1 works perfectly, right? A sidenote: the usb dac got installed every time I plug it in the pc, is it supposed to do so?
 
What do I have to check about the U3? The solder joints? Some voltages?

 

[tomb]

Quote:

Ok, this means that the U1 works perfectly, right? A sidenote: the usb dac got installed every time I plug it in the pc, is it supposed to do so?
 
What do I have to check about the U3? The solder joints? Some voltages?

Have you got some pics of the PCB?  That might tell us what's going on a lot faster than exhausting every possibility by typing posts.
 
That said, no - there is a possibility that U1 is not working perfectly.  There are a number of traces (through vias to the backside of the PCB) that connect to U3.  Obviously, this is true: the PCM2706/7 takes the USB signal and converts it into a digital stream that the Wolfson chip can convert to analog.  So, there are 4 traces that connect U1 to U3.  If one of those is messed up, or the pin connections to those traces, then U3 is not going to operate.  Three of those traces are on the USB-side of U1 and the fourth trace is on the side next to U3.
 
Even so, it's been my experience that if the DAC is recognized by the PC, then U1 is all OK.  You raise a good point about every time you connect it, the PC re-installs it.  So, maybe the U1 chip is not working "perfectly."  We're all just making guesses here.  That's what you should do in troubleshooting - try and eliminate all the possibilities.  One of the best things to check is if there is continuity between the U1, U3 chip pins and their traces.  Or, you might try posting pics of your PCB and see if any of us can spot something.

 

[Avro_Arrow]

It has been my experience, that once installed, it doesn't install it again
as long as you use the same USB port. If you use a different port, it
see it as a whole new device and installs it again and gives it the next
number in the sequence.

 

[acvtre]

Quote:

It has been my experience, that once installed, it doesn't install it again
as long as you use the same USB port. If you use a different port, it
see it as a whole new device and installs it again and gives it the next
number in the sequence.

Infact I've just plugged it in again and the pc recognized it immediately. Thanks!
Quote:

Have you got some pics of the PCB?  That might tell us what's going on a lot faster than exhausting every possibility by typing posts.
 
That said, no - there is a possibility that U1 is not working perfectly.  There are a number of traces (through vias to the backside of the PCB) that connect to U3.  Obviously, this is true: the PCM2706/7 takes the USB signal and converts it into a digital stream that the Wolfson chip can convert to analog.  So, there are 4 traces that connect U1 to U3.  If one of those is messed up, or the pin connections to those traces, then U3 is not going to operate.  Three of those traces are on the USB-side of U1 and the fourth trace is on the side next to U3.
 
Even so, it's been my experience that if the DAC is recognized by the PC, then U1 is all OK.  You raise a good point about every time you connect it, the PC re-installs it.  So, maybe the U1 chip is not working "perfectly."  We're all just making guesses here.  That's what you should do in troubleshooting - try and eliminate all the possibilities.  One of the best things to check is if there is continuity between the U1, U3 chip pins and their traces.  Or, y
 
 
 
 
 
ou might try posting pics of your PCB and see if any of us can spot something.

Some pics: 

 
I've just tested the voltage between a pin of the U1 and one of the U3 chosen at random and found continuity.

 

[tomb]

Well, after studying these pics pretty extensively, I don't see any bridges in the pins of U1 and U3.  That leaves a couple of possibilities: 1) your wiring is messed up or shorted - can't tell what's going on with those output wires and whether you have them shorted, perhaps, or 2) the DAC chip is burned up.  At least in one photo, the chip and pins look like it went through a lot.  I don't know this for certain, but I think the PCM2706/7 can take a lot more abuse than the Wolfson DAC chip.  The fact that the DAC chip is smaller may mean it can't dissipate as much heat while it's being soldered.
 
The 3.3V should be OK, or U1 wouldn't work and it wouldn't be recognized by the PC.  The DAC chip uses the same voltage.  Unfortunately, all the voltage conversion for the analog output is internal to the Wolfson DAC.  Because of the charge pump inside the DAC chip, there should be zero DC on the outputs anyway.  So, attempting to measure the AC signal voltage at output would be problematic.  You could confirm for us that there is no offset in the output - that would at least eliminate one red flag.  Hopefully, your DAC chip is OK. 
 
Also - I can't tell from the pics, but you should look at your clock oscillator.  Sometimes people have gotten the solder from the pads over on top of the oscillator.  If the solder is touching both the metal top and one of the pads, the oscillator will be shorted out.  I sort of think the PCM2706/7 wouldn't work, either, but I'm not certain.  Anyway, that's another thing to check.
 
The next step you might take is to trim all those leads on the bottom of the PCB from the through-hole parts and the wiring.  Then make sure that the wiring to your outputs is correct, not shorted, etc.  Use your meter to determine continuity or any shorts.