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The GrubDAC - Page 65

post #961 of 1073
Quote:
Originally Posted by tomb View Post

...snip...

The pics of the clock:

 

 

As you can see the clock doesn't seem to have solder on its top.

 

Sorry for the noob question, but how can I measure the offset?


Edited by acvtre - 6/29/13 at 10:00am
post #962 of 1073
Quote:
Originally Posted by acvtre View Post
<snip>

 

As you can see the clock doesn't seem to have solder on its top.

 

Sorry for the noob question, but how can I measure the offset?

Put one probe on the ground pad at the input and the other at the signal output - either Left or Right signal wire.  See if you measure any DC voltage.

post #963 of 1073
Quote:
Originally Posted by tomb View Post

Put one probe on the ground pad at the input and the other at the signal output - either Left or Right signal wire.  See if you measure any DC voltage.

Measured also the offset voltage. I measure something like 2.7mV, so really really low DC voltage, it should be ok, right?

 

A thing that I'm not sure about is if every pin of the U3 is soldered.

post #964 of 1073
Quote:
Originally Posted by acvtre View Post

Measured also the offset voltage. I measure something like 2.7mV, so really really low DC voltage, it should be ok, right?

 

A thing that I'm not sure about is if every pin of the U3 is soldered.

Yes, 2.7mV is not bad.  It should be lower, but we can't tell what kind of meter you have and that may be at the limits of its precision.  Still, it doesn't sound like a worry.

 

As for checking the pins on U3 - this should be done carefully (power off!), but you should be able to place one probe of your meter on top of the pin as it exits the chip's plastic body and then follow the trace the pin is supposed to be soldered to another place on the PCB.  Place your other probe there.  Measure for zero resistance.  If you get something else, chances are the pin is not soldered.  You have to be careful with the right touch, though, because it's possible to press down hard enough on the pin to make contact with the trace even if it's not really soldered.

 

Similarly, you can place your probes on adjacent pins to see if they're bridged (zero resistance).  You have to reference this to the schematic/layout on the GrubDAC website, however, because several pins are supposed to be connected together.


Edited by tomb - 6/30/13 at 6:49am
post #965 of 1073

I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?

post #966 of 1073
Quote:
Originally Posted by mikechml View Post
 

I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?

 

Unfortunately, I'd have to say this is normal.  It may be a by-product of a high-performance DAC (meaning a fairly high current draw) under current limits of a USB buss.  The transient current draw may be too much for the PC.  I've accepted it as an irritation, nothing more.

 

Things could be a lot worse - on the Alien or BantamDAC, it usually meant the DAC was fried.;)  I had it happen to me today at work with my pupDAC and a Mini3 (no damage, though!).  This happened even with a powered USB hub while I was plugging power into the Mini3 - but it was turned on when I was doing it - probably not a good idea.  I've also had the same thing happen with external (self-powered) USB disc drives.  I've had to un-plug and re-plug them back in before they were recognized by the PC again.

 

Bottom line, I would always be careful with power plug-ins/un-plugs when USB devices are connected.


Edited by tomb - 9/6/13 at 5:01am
post #967 of 1073
Thread Starter 
Quote:
Originally Posted by mikechml View Post
 

I'm having some trouble with my GrubDAC. Whenever I switch my amp (Little Dot I+) on or off it puts the dac into a sort of frozen state which requires the USB to be disconnected and reconnected for it to go back to normal. Any ideas on what might be happening, what I should test and any possible solutions?

 

As Tom has said, this appears to be normal.  I have some suspicions as to what causes it, but haven't had time to track it down. 

 

It does appear to be related to spikes on the mains power that get fed into the dac (either via to output or the PC side).  Similar kinds of things happen when I run turn on/off a desktop lamp near my rig.

 

As a test, if you are comfortable with removing parts, I might try to remove C5.

post #968 of 1073
So I built my grubdac a couple years ago and due to various circumstances I never managed to get it working. Yesterday I finally got to work and fixed a bridge on u2 so now it works.

But here's the catch, it will work for a bit, but then The sound will cut out, and reconnecting it doesn't change it. I also have some issues of the device not being recognized on Linux. I'll have pics up in an hour or so, but any ideas of common faults in the meantime?
post #969 of 1073
Quote:
Originally Posted by zhoob2004 View Post

So I built my grubdac a couple years ago and due to various circumstances I never managed to get it working. Yesterday I finally got to work and fixed a bridge on u2 so now it works.

But here's the catch, it will work for a bit, but then The sound will cut out, and reconnecting it doesn't change it. I also have some issues of the device not being recognized on Linux. I'll have pics up in an hour or so, but any ideas of common faults in the meantime?

It's all still related.  All USB connections are governed by U1, the PCM2707/6 chip, and the 3.3VDC power supply necessary to power it - U2.

post #970 of 1073
3v3 is good, even when it stops responding, just to put that out there. I suppose I'll try to reflow everything again and take pics

Sent from my One using Tapatalk
post #971 of 1073
Quote:
Originally Posted by zhoob2004 View Post

3v3 is good, even when it stops responding, just to put that out there. I suppose I'll try to reflow everything again and take pics

Sent from my One using Tapatalk

Then there's something probably going on with the PCM chip.

 

The GrubDAC may get knocked offline if there's a power issue - something gets plugged-in/un-plugged, some other power load turning on or off, etc.  It should not refuse to re-connect, however, and there shouldn't be an issue with Linux.

post #972 of 1073
Well now I'm only getting ~1v on the 3v3 so I guess I'll work on that and see what happens
post #973 of 1073
Quote:
Originally Posted by zhoob2004 View Post

Well now I'm only getting ~1v on the 3v3 so I guess I'll work on that and see what happens

Makes sense - good luck!

post #974 of 1073

ok, so I fixed the 3v3 (didn't connect fully when I resoldered it).

 

now the symptom I'm having is it connects just fine, recognized by lsusb and alsa. Then, after a short bit, I lose it and dmesg says "Port disabled by hub (EMI?), re-enabling..." after which, it doesn't show up.

 

here is a pic of the topside I just took, not sure if you can see anything or not,

 

http://img9.imageshack.us/img9/9046/4ukb.jpg

 

or at least there would be if I had upload permissions. I'll see if after I post this I have enough posts and then I can edit this one with it, or I'll just use imageshack or something.


Edited by zhoob2004 - 10/20/13 at 4:33pm
post #975 of 1073
Quote:
Originally Posted by zhoob2004 View Post
 

http://img9.imageshack.us/img9/9046/4ukb.jpg

 

 

I'd look at getting some solder wick and getting rid of the extra solder on the crystal oscillator. I had problems on my pupdac with too much solder on the oscillator shorting against the case (was so small I didn't notice it initially). USB hubs will disable devices if they draw too much power, so that's an option too, although you should have noticed regulators/inductors getting super-hot.

 

Is that a small bridge lower right-side of the PCM2706?

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