[cobaltmute]

If it is a cable dac, i.e the usb cable is attached, are you sure D+ and D- from your USB cable are soldered to the right places? Reversing them will have Windows recognize the DAC but say it has malfunctioned.

 

[mfaughn]

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif If it is a cable dac, i.e the usb cable is attached, are you sure D+ and D- from your USB cable are soldered to the right places? Reversing them will have Windows recognize the DAC but say it has malfunctioned.

I've got green to D+ and white to D-. That is the USB standard color coding. I suppose it can't hurt to try swapping them.

edit: that wasn't it either...

 

[nullstring]

have you tried reflowing the solder around the chips?

I've heard that fix issues like this plenty of times

 

[mfaughn]

Quote:

Originally Posted by nullstring /img/forum/go_quote.gif have you tried reflowing the solder around the chips? I've heard that fix issues like this plenty of times

yup, done that. also have ohmed out all the pins from the top of the chip to the edge of each pad. Next will be an attempt to ohm out from each active pin on the chip to where it connects on the board so that there is a trace between the test points. If that checks out then I think I'm going to bag it and try new ICs.

Anyone know if those voltages looked reasonable? I found some other forum discussion on PCM2707 problems and their voltages where quite different than mine for some of those locations.

Thanks to y'all for trying to help me out.

-Michael

 

[cobaltmute]

Okay, a couple of more ideas:

- from the 3.3V side of L3 to D+, what is your resistance (power off)?
- from D+ to pin 23 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.
- from D- to pin 22 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.
- Check from D+ to D- to see if there is any shorts.

As well, it would help if you gave us the full message of the error to understand if it is a communication error or a power error.

If you check in Windows Device Managment, does it show any USB port being down after insertion?

 

[cobaltmute]

The voltages are all good. The ones that are low are that way as we are not powering any portion of the headphone amp portion of the PCM.

 

[cobaltmute]

Michael,

Forgot to add, what are your C9 and C10?

 

[mfaughn]

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif Okay, a couple of more ideas: - from the 3.3V side of L3 to D+, what is your resistance (power off)?

1500 ohms

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif - from D+ to pin 23 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.

22.2 ohms

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif - from D- to pin 22 on the PCM2707, what is the resistance (power off)? Please try to be very gentle so that you can test to see if the pin is soldered down properly on the PCM2707.

22.2 ohms

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif - Check from D+ to D- to see if there is any shorts.

2.73 megohms

D+ to pin 22 is the same
D- to pin 23 is closer to 1.9 megohms

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif As well, it would help if you gave us the full message of the error to understand if it is a communication error or a power error. If you check in Windows Device Managment, does it show any USB port being down after insertion?

I took the usb cable off for the moment and I'll have to put it back on to check for the verbatim message. I am 90% sure that it is a com error. Windows says the device is unrecognized and has malfunctioned. It shows up as a connected device and windows says there is no driver.

 

[cobaltmute]

mfaughn,

All of your power readings are OK. All of your resistances are OK and match what I would expect.

The only time I have seen comm errors is when the D+ and D- have been reversed. I learned that one the hard way as the error was on the PCB. I'm leaning away from this right now as your resistance checks are good.

The other time that I have seen errors in Windows is due to power errors. These are usually due to the board pulling too much power.

My next tests are:
- can you put a meter between the USB cable and the board and determine how much current it is pulling?
- check around U1, C9, R8, the LED, L2 for any shorts.

The exact error message and pictures are starting to become really important. All of us have done bad soldering so don't be embarrassed. As well, can you let us know what hardware you are using this with - PC, Laptop, netbook, directly attached or through a hub, etc. The more you give us the more we can help.

 

[cobaltmute]

I was just checking on the online BOM for the grubDAC listed in the first post and the fates have aligned and everything is in stock again for those few that may still be ordering parts.

For those that have built it and lived with it for a while, any more comments? There may be some production boards coming in the future

 

[blippster]

Not sure if this was mentioned before, but perhaps you could modify the output vias to be slightly larger, to accommodate around 22 gauge wire? I've completed my three already, but for at least one had to trim the wires I was using as they were too thick to fit in.

 

[Billyk]

Hey thanks! Been waiting a while for Mouser and kinda forgot this one. I'll finally get to finish it. Thanks again!

 

[ujamerstand]

well, I've finished building one of these today, but ran into some snags. At first, the dac is recognized by the usb, but no music plays. Then the device shuts off completely.

TPS regulator was hot when touched, I think its burnt to a crisp. I've determined that there is a solder bridge in the tps regulators' pin 1 and 2 that caused this. After replacing the device with a spare, with no solder bridge, the device doesn't even get recognized by the computer. voltage reading over c7 is zero. How is this possible?! I've just switched to a new device! What kind of sacrifice do I have to prepare to get this thing working? =.=''

 

[cobaltmute]

We'll see what kind of sacrifice

So first check: Pin 1 of U1 to gnd (the pad with the via) - this should be ~5V as this is raw USB

Then either end of L3 to gnd - this should be 3.3V.

Use the GND of the outputs

Also check from the GND beside the usb connector to gnd for output for resistance - this should be low. Check the resistance of L2 as well. If you shorted to ground, the ferrites may have gone as they can only handle so much current.

 

[ujamerstand]

Pin 1 of U1 to usb gnd returns 4.85V, and L3 to gnd returns zero. usb gnd to output gnd is low, around 68. the resistance of L2 to gnd is infinite, or are you talking about the resistance across L2? in that case its farely low at 1.8Ohms, I'm guessing I burnt the second regulator while soldering... Else L3 to gnd should have returned 3.3V. I will attempt to replace U1 with a third one tomm. In the main time, sacrifice will be tender stake tonight.