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The GrubDAC - Page 67

post #991 of 1073
Quote:
Originally Posted by cobaltmute View Post
 

 

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.

 

So I finally got some time to get back to debugging this. Thanks for the info.

 

Removing C5 didn't help.

I'm currently using the setup with my laptop and it's made the problem a bit easier to track down, it also reconnects the DAC automatically which is nice. I'm fairly sure that it's a spike being fed back from the mains via the output to the amp, I can trigger the problem by turning my soldering iron off (plugged into the same strip as the amp) while the DAC is powered from my laptop (on battery power). dmesg log below.

I'm also finding that the DAC is unusable when my laptop is plugged into the mains. I am using a cheap replacement charger though so that's probably not helping.

 

Any ideas for workarounds?

 

I'll try to get some 'scope shots of what's happening on the grubdac outputs after the holidays.

 

Quote:
 

[20837.640106] usb 3-1: new full-speed USB device number 19 using uhci_hcd
[20837.834359] usb 3-1: New USB device found, idVendor=08bb, idProduct=2706
[20837.834372] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[20837.834379] usb 3-1: Product: USB Audio DAC   
[20837.834386] usb 3-1: Manufacturer: Burr-Brown from TI              
[20837.866346] input: Burr-Brown from TI               USB Audio DAC    as /devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1:1.2/input/input215
[20837.866497] hid-generic 0003:08BB:2706.00CC: input,hidraw0: USB HID v1.00 Device [Burr-Brown from TI               USB Audio DAC   ] on usb-0000:00:1a.0-1/input2
[20840.088265] hub 3-0:1.0: port 1 disabled by hub (EMI?), re-enabling...
[20840.088275] usb 3-1: USB disconnect, device number 19
[20840.380109] usb 3-1: new full-speed USB device number 20 using uhci_hcd
[20840.575289] usb 3-1: New USB device found, idVendor=08bb, idProduct=2706
[20840.575297] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[20840.575301] usb 3-1: Product: USB Audio DAC   
[20840.575304] usb 3-1: Manufacturer: Burr-Brown from TI              
[20840.606463] input: Burr-Brown from TI               USB Audio DAC    as /devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1:1.2/input/input216
[20840.606776] hid-generic 0003:08BB:2706.00CD: input,hidraw0: USB HID v1.00 Device [Burr-Brown from TI               USB Audio DAC   ] on usb-0000:00:1a.0-1/input2

post #992 of 1073

I finished building my first grubdac yesterday. Washed it with flux cleaner then waited for today to try it.

 

The moment I plugged it in, U2 went up in smoke.

 

Has this happened to anyone else? Any tips as to what may have caused it?

 

Sorry I don't have anything to take usable pictures.

post #993 of 1073
Quote:
Originally Posted by KimLaroux View Post
 

I finished building my first grubdac yesterday. Washed it with flux cleaner then waited for today to try it.

 

The moment I plugged it in, U2 went up in smoke.

 

Has this happened to anyone else? Any tips as to what may have caused it?

 

Sorry I don't have anything to take usable pictures.


I'm not quite sure that it's happened to anyone else, although we've perhaps had plenty who have mentioned U2 getting hot.  The GrubDAC is not a complex build.  It's really a matter of soldering all the pins correctly on the SMD chips like U1, U2, and U3.  If U2 went up in smoke, something was shorted, plain and simple.

 

You state you "don't have anything to take usable pictures."  Unfortunately, that would be the first suggestion: post some clear photos to see if anyone can see the short. 

post #994 of 1073

I planned on ordering a few U2 with my Carrie order. Sadly the part number listed in the BOM (595-TPS79333DBVRQ1) is out of stock for the next 17 weeks. Is there an alternative to this chip I can find at Mouser? 

post #995 of 1073
Quote:
Originally Posted by KimLaroux View Post
 

I planned on ordering a few U2 with my Carrie order. Sadly the part number listed in the BOM (595-TPS79333DBVRQ1) is out of stock for the next 17 weeks. Is there an alternative to this chip I can find at Mouser? 


Yes, any TPS79333 will work with the same planform (not sure it comes in any other package).

 

Simply type in "TPS79333" in the Mouser search.  The first one I get (in a list of 6) says there's 13,954 in stock at 84 cents each. (TPS9333DBVR) 

post #996 of 1073
Quote:
Originally Posted by tomb View Post
 


Yes, any TPS79333 will work with the same planform (not sure it comes in any other package).

 

Simply type in "TPS79333" in the Mouser search.  The first one I get (in a list of 6) says there's 13,954 in stock at 84 cents each. (TPS9333DBVR) 

 

Thanks! With that, I managed to order everything from Mouser. It's great not having to place a second order from a second supplier and not pay shipping again.

 

:smile:

post #997 of 1073

Ok I replaced U2 and I get the same problem.

 

I checked for shorts trough a lamp, nothing.

 

I measured for shorts using my multimeter. Nothing between pins on the chips. Measuring between 3V3 and 0V, I get 1.5K one way once caps are charged, and 485R the other way.

 

The 3V3 rail moves up and down around 2.3V. U2 is burning up again and smelling like magic smoke.

 

*scratches head*

 

Edit : 

 

The first time I plugged the DAC today, nothing showed up on Dmesg and U2 was not heating up, though the 3V3 rail was still at 2.3V

 

The second time I connected it, after reflowing a few pins, U2 heated up and smelled like burned electronics, but I got this on Dmesg:

 

[17427.235222] usb 6-1: new full-speed USB device number 2 using uhci_hcd
[17427.348134] usb 6-1: device descriptor read/64, error -71
[17427.561130] usb 6-1: device descriptor read/64, error -71
[17427.764223] usb 6-1: new full-speed USB device number 3 using uhci_hcd
[17427.877117] usb 6-1: device descriptor read/64, error -71
[17428.090227] usb 6-1: device descriptor read/64, error -71
[17428.293197] usb 6-1: new full-speed USB device number 4 using uhci_hcd
[17428.702118] usb 6-1: device not accepting address 4, error -71
[17428.804114] usb 6-1: new full-speed USB device number 5 using uhci_hcd
[17429.212084] usb 6-1: device not accepting address 5, error -71
[17429.212127] hub 6-0:1.0: unable to enumerate USB device on port 1
[17494.544134] usb 6-1: new full-speed USB device number 6 using uhci_hcd
[17494.656125] usb 6-1: device descriptor read/64, error -71
[17494.869131] usb 6-1: device descriptor read/64, error -71
[17495.072226] usb 6-1: new full-speed USB device number 7 using uhci_hcd
[17495.185108] usb 6-1: device descriptor read/64, error -71
[17495.399106] usb 6-1: device descriptor read/64, error -71
[17495.602128] usb 6-1: new full-speed USB device number 8 using uhci_hcd
[17496.011113] usb 6-1: device not accepting address 8, error -71
[17496.113137] usb 6-1: new full-speed USB device number 9 using uhci_hcd
[17496.522119] usb 6-1: device not accepting address 9, error -71
[17496.522162] hub 6-0:1.0: unable to enumerate USB device on port 1

 

 

Edit 2 : 

 

Apparently I'm not the first to have this problem http://www.head-fi.org/t/445155/the-grubdac/660#post_7350187

Sadly the person gave up and built a new kit. 


Edited by KimLaroux - 2/19/14 at 4:06pm
post #998 of 1073

It's possible the PCB has a fault.  We sell them pretty cheaply and an electrical check wasn't included in the production order.  That said, I'm only really aware of one, perhaps two that had a defect.

 

We could still use some pics.  There's definitely a short somewhere, or U2 would not heat up like that.

post #999 of 1073

I reflowed everything, reseated some parts that were not perfectly aligned. I then gave it a shower of flux cleaner and cleaned it with a brush. I'll leave it to dry over night and try again tomorrow. 

 

I'll borrow a friend's camera and take pictures Friday. 

post #1000 of 1073

Well, this is interesting.

 

Plugging the DAC today, it's still not recognized. I get the same dmesg error. I had the same 2.3 V when I plugged it in.

 

But the voltage slowly rose, and leaving it plugged for a while, it slowly rose to 3.30 V. Reconnecting the USB cable doesn't change anything though, it's still not recognized.

 

This is simply Le weird.

 

Is there a way to debug the PCM2707 to verify if it's working?

post #1001 of 1073
Quote:
Originally Posted by KimLaroux View Post
 

Well, this is interesting.

 

Plugging the DAC today, it's still not recognized. I get the same dmesg error. I had the same 2.3 V when I plugged it in.

 

But the voltage slowly rose, and leaving it plugged for a while, it slowly rose to 3.30 V. Reconnecting the USB cable doesn't change anything though, it's still not recognized.

 

This is simply Le weird.

 

Is there a way to debug the PCM2707 to verify if it's working?


If there is a way to debug a PCM2707, I'm not aware of it.  I once built a pupDAC and used too-high a soldering temperature on my Hakko.  It fried the PCM2707, but it was h*ll figuring that out.

 

Despite that statement above, I can't seriously suggest that's what happened to your DAC - sight unseen.  I still think something is shorting out.  In my case above, every single voltage on the PCB was right on.  It just didn't work.  Yours seems to be a different issue.

post #1002 of 1073

Hi Kim.

 

Checking for shorts (the most likely cause) only takes a few minutes on an IC, you just walk the probes along the row of pins. 

 

There are only a limited number of pins on this board. The next thing is to go through them all with a DMM set to beep, making sure that all the connections that should be made, are made, and that there are none that shouldn't. You may be able to get a netlist, most schematic capture packages export one to their accompanying PCB layout tool, and many export one in a standard format. If not, writing one is not that big a job for a board this simple, and working from the netlist is less hassle than working from the schematic.

 

Once you're satisfied that the connectivity is good, then is the time to start thinking about component issues. 

 

It's depressing when things don't work, and it's easy to slide into thinking along the lines 'I'll never get to the bottom of this', but all build faults eventually yield to steady, grinding application.

 

w

post #1003 of 1073

Great post, Waki - thanks!

 

Let us know what you find, Kim!

post #1004 of 1073
Quote:
Originally Posted by tomb View Post
 


If there is a way to debug a PCM2707, I'm not aware of it.  I once built a pupDAC and used too-high a soldering temperature on my Hakko.  It fried the PCM2707, but it was h*ll figuring that out.

 

Despite that statement above, I can't seriously suggest that's what happened to your DAC - sight unseen.  I still think something is shorting out.  In my case above, every single voltage on the PCB was right on.  It just didn't work.  Yours seems to be a different issue.

 

 

Ah snap! That could very well be it! My iron was set very hot, as I was using it for large point to point soldering. I did not think about lowering it as I figured it wasn't gonna be an issue if I left the iron on the pins only a second. But with the number of pins on those chips, I could have over-heated it.

 

How did you come to the conclusion the chip was fried? Any definitive test I can run?

 

Quote:
Originally Posted by wakibaki View Post
 

Hi Kim.

 

Checking for shorts (the most likely cause) only takes a few minutes on an IC, you just walk the probes along the row of pins. 

 

There are only a limited number of pins on this board. The next thing is to go through them all with a DMM set to beep, making sure that all the connections that should be made, are made, and that there are none that shouldn't. You may be able to get a netlist, most schematic capture packages export one to their accompanying PCB layout tool, and many export one in a standard format. If not, writing one is not that big a job for a board this simple, and working from the netlist is less hassle than working from the schematic.

 

Once you're satisfied that the connectivity is good, then is the time to start thinking about component issues. 

 

It's depressing when things don't work, and it's easy to slide into thinking along the lines 'I'll never get to the bottom of this', but all build faults eventually yield to steady, grinding application.

 

w

 

I did check for shorts between every pins on the chips. Nothing.

 

What's a netlist?

 

And in case you haven't noticed, you're talking to a girl who took over 2 years to design, build, (debug, redesign, rebuild)*20 an hybrid amp. Giving up is not one of my virtues. ;)  I'm just learning along, so it takes a while.

post #1005 of 1073
Quote:
Originally Posted by KimLaroux View Post
 

 

 

What's a netlist?

 

 

 

A netlist is a term used in board design.

 

It is simply a list of which pin is connected to which other pin or pins.

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