The GrubDAC - Page 63

Quote:

Originally Posted by daves440 

O.K.Yes it is availible at Beezar, Thank you Tom and Scot. I will let you know how it worked out.!

Just curious, but are you aware of the grubDAC website?  Anything you want to know about the grubDAC is there:

http://www.diyforums.org/GrubDAC

Quote:

Originally Posted by tomb 

Just curious, but are you aware of the grubDAC website?  Anything you want to know about the grubDAC is there:

http://www.diyforums.org/GrubDAC

Quote:

Originally Posted by daves440 

O.K.Yes it is availible at Beezar, Thank you Tom and Scot. I will let you know how it worked out.!

No problem - I think I realized who you are, now.

Hi,

I just built my grubDac two days ago. It detects fine in Windows 7, but there is a kind of digital noise coming from the speakers when no source is playing. I think I can hear something not right when music is playing but cannot put my finger on it.

I have checked and rechecked everything. shining a strong light through the PCB to check for bridges, reflowed some pins etc etc. checking with my 5X lupe I cannot see anything wrong.

Any ideas? btw, I have been looking through this thread and google without finding a solution. I mean, it is ALMOST working perfectly :)

Quote:

Originally Posted by hyperion007 

Hi,

 

I just built my grubDac two days ago. It detects fine in Windows 7, but there is a kind of digital noise coming from the speakers when no source is playing. I think I can hear something not right when music is playing but cannot put my finger on it.

 

I have checked and rechecked everything. shining a strong light through the PCB to check for bridges, reflowed some pins etc etc. checking with my 5X lupe I cannot see anything wrong.

 

Any ideas? btw, I have been looking through this thread and google without finding a solution. I mean, it is ALMOST working perfectly :)

Usually - if it's audible noise, it's something in the analog output.  This may sound silly, but check your output connections - do you have good solder joints at the leads, no stray wires intermittently touching the other pads, ground wires have good, solid connections to the ground pads?

After a friend of mine took the PCB to work and had a look at it under a microscope and re-soldered everything I had high hopes for a working grubDAC tonight. No such luck. The LED was still flickering and the sound was clipping and sounding terrible.

I then utilized my new hot air rework station and a generous amount of flux to both ICs, still the same problem. 

Stable 3.3V and 5V

I have had it hooked up to a Trust USB 2.0 hub, but for no reason we tried hooking it up to a USB port on the motherboard instead, and TADAAAAA! no more flickering LED and sounds great!

The USB hub is externally powered and only had two bluetooth dongles in it so should have plenty of power so I don't know why it was acting the way it was.

Anyway, thought I would share this with everyone in case someone has the same problem.

/Daniel S

Quote:

Originally Posted by hyperion007 

After a friend of mine took the PCB to work and had a look at it under a microscope and re-soldered everything I had high hopes for a working grubDAC tonight. No such luck. The LED was still flickering and the sound was clipping and sounding terrible.

I then utilized my new hot air rework station and a generous amount of flux to both ICs, still the same problem. 

 

Stable 3.3V and 5V

 

I have had it hooked up to a Trust USB 2.0 hub, but for no reason we tried hooking it up to a USB port on the motherboard instead, and TADAAAAA! no more flickering LED and sounds great!

 

The USB hub is externally powered and only had two bluetooth dongles in it so should have plenty of power so I don't know why it was acting the way it was.

 

Anyway, thought I would share this with everyone in case someone has the same problem.

 

 

/Daniel S

Yep - I think people have been having similar problems with the ODAC.  I would worry about the PupDAC being connected to some sort of hub, too.  A high-quality, linear-regulated USB audio DAC is going to pull a lot of current and if the USB connection is not adequately supplied, it will drop voltage and knock off the DAC or cause other issues.  I can't speak for cobaltmute, the grubDAC/SkeletonDAC/PupDAC designer, but as DIY-er's, I would think one would design almost to the limits of the USB connection - on purpose.  That would ensure that one was getting the best possible performance from what is available for the design.

So, yes - glad to hear that everything is OK and we should probably all take care in where we plug-in a quality audio USB-powered DAC.

Quote:

Originally Posted by tomb 

Quote:

Originally Posted by hyperion007 

After a friend of mine took the PCB to work and had a look at it under a microscope and re-soldered everything I had high hopes for a working grubDAC tonight. No such luck. The LED was still flickering and the sound was clipping and sounding terrible.

I then utilized my new hot air rework station and a generous amount of flux to both ICs, still the same problem. 

 

Stable 3.3V and 5V

 

I have had it hooked up to a Trust USB 2.0 hub, but for no reason we tried hooking it up to a USB port on the motherboard instead, and TADAAAAA! no more flickering LED and sounds great!

 

The USB hub is externally powered and only had two bluetooth dongles in it so should have plenty of power so I don't know why it was acting the way it was.

 

Anyway, thought I would share this with everyone in case someone has the same problem.

 

 

/Daniel S

Yep - I think people have been having similar problems with the ODAC.  I would worry about the PupDAC being connected to some sort of hub, too.  A high-quality, linear-regulated USB audio DAC is going to pull a lot of current and if the USB connection is not adequately supplied, it will drop voltage and knock off the DAC or cause other issues.  I can't speak for cobaltmute, the grubDAC/SkeletonDAC/PupDAC designer, but as DIY-er's, I would think one would design almost to the limits of the USB connection - on purpose.  That would ensure that one was getting the best possible performance from what is available for the design.

 

So, yes - glad to hear that everything is OK and we should probably all take care in where we plug-in a quality audio USB-powered DAC.

I still have not built mine, but I have the opposite problem. My onboard usbs are too low-current to power my external harddrive much at all, when I hook it up to my hub, I get 10x the data transfer speeds, maybe even more.

Oops, that was meant about the Pupdac, but well the statements about the usb ports stands.

What is the output impedance of the grubDAC? I want to hook it up to a PGA4311 that needs a source impedance of 600 Ohms or less.

I haven't found this information anywhere.

Quote:

Originally Posted by hyperion007 

What is the output impedance of the grubDAC? I want to hook it up to a PGA4311 that needs a source impedance of 600 Ohms or less.

 

I haven't found this information anywhere.

110 ohms

I was hoping that I wouldn't need to post here for help but I am stumped.  While I have a decent amount of experience soldering, this is first time with SMDs.  I tried search the forum for similar issues and answers with no luck.  So here I go....

Everything is soldered on the board except for the leads going out.  I plugged in the device to my Windows 7 desktop and it showed it trying to install the drivers for 3 different components (one was a USB DAC) but it failed.  Unplugged and plugged back in, and this time shows up as Unknown Device.  I then notice a small amount of smoke coming from the PCM chip.  Unplug again found a bridge and fixed it.  Plug back in, no smoke, but nothing from the computer.  Ugh!  I start searching for another bridge.  I suspected there was one near C9 but I failed to desolder the excess and in my tired state I try to scrape it off but realized that is the ground plate it should make a difference if there is a bridge there. Gave up for the day.

Next day, I started testing continuity on the chips but nothing stuck out. I tried it on my laptop this time with nothing else plugged in the usb ports.  After plugging it in, I didnt see anything happening so I unplugged but right after that Windows should a notification that the device was properly installed with a USB DAC listed.  So plugged it back in, but the device shows up as Unknown Device again and every time I try again.  LED is lighting up and the voltage on the LED leads shows 3.24v .

I also want to note that the LED is mounted upside-down on purpose and the I replaced C1, C5 and C15 capacitors with these: http://www.mouser.com/Search/ProductDetail.aspx?R=ECA-0JHG471virtualkey66720000virtualkey667-ECA-0JHG471

Is the PCM fried?  Is there any thing else I can test?  Any advise or suggestions would be helpful!

It looks like there are 3 or 4 bridged pins on the USB chip.

Quote:

Originally Posted by scootsit 

It looks like there are 3 or 4 bridged pins on the USB chip.

I think I am missing something then.  Can you point them out? 

The only bridges I see are on the U1 in accordance with the board layout.

Quote:

Originally Posted by Caretaker007 

I think I am missing something then.  Can you point them out? 

 

The only bridges I see are on the U1 in accordance with the board layout.

 

There are only two "bridges" by the traces on the PCB.  Your circle in the upper right is a solder bridge.

It looks like R9 is only soldered on one side, too (on the backside of the PCB). (EDIT: Could be the angle of the photo.  I was going to say R5, too, but it looks fine in one pic.)  You might look at that, too.  Your work looks pretty good.  Hopefully, the PCM chip is not damaged and things will work when you get this fixed.

Quote:

Originally Posted by tomb 

There are only two "bridges" by the traces on the PCB.  Your circle in the upper right is a solder bridge.

 

It looks like R9 is only soldered on one side, too (on the backside of the PCB). (EDIT: Could be the angle of the photo.  I was going to say R5, too, but it looks fine in one pic.)  You might look at that, too.  Your work looks pretty good.  Hopefully, the PCM chip is not damaged and things will work when you get this fixed.

Is the layout here out of date for U1: http://www.diyforums.org/GrubDAC/layout/GrubDAC-laytop.jpg

The upper right circle is just a ground "bridge".  Either way, I forced the removal of the bridge but that pin is still grounded.

R9 looks ok, Resistance from C17 to C12 is 110 Ohms as expected. 

R5 also checks out ok. Reflowed both resistors just to be sure.

Still showing up as a Unknown Device.  Do I need to replace the PCM chip?

He's right Tom,,,the three bridges are part of the board.

See this photo: GrubDAC PCB.