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Gamma-2 (γ2) DAC Thread
Sep 26, 2009 at 2:18 PM Post #676 of 2,154
Why must U1 be so darn close to C3... Both regulators on the y2 gave bad voltages, but managed to get the 3.3V one working. What does pin 4 do? I feel that it may not be making contact with the board, that or pin 5...

Edit: I'll probably bypass it for the time being... when I fix my desoldering pump I'll have a go at desoldering C3.

#2: I think the leg for pin 5 disappeared or was never there in the first place... I hope it didn't melt inside...

#3: Nothing will happen if I leave y2.U1 out but leave the power for the ASRC intact, right? I desoldered U1 already but stopped short of tapping y1's 4.5V regulator.
 
Sep 26, 2009 at 3:09 PM Post #677 of 2,154
Quote:

Originally Posted by Henrik Nordberg /img/forum/go_quote.gif
You have "SPDIF" on the front and "S/PDIF" on the back. Minor but I would change the front one to "S/PDIF".

Cheers,
- Henrik


I told myself to go change that and promptly forgot about it. Thank you for reminding me - I'd have been pretty incensed with myself if I'd ordered the panels with an inconsistency like that.
smily_headphones1.gif
 
Sep 26, 2009 at 5:55 PM Post #678 of 2,154
Quote:

What does pin 4 do? I feel that it may not be making contact with the board, that or pin 5....


Pin 4 is the noise reduction or Bypass pin, in either case the pin is connected to an external capacitor which helps improve the performance of the regulator.
Pin 5 is the output.


Quote:

#3: Nothing will happen if I leave y2.U1 out but leave the power for the ASRC intact, right? I desoldered U1 already but stopped short of tapping y1's 4.5V regulator.


U1 is the 4.5 or 4.75 volt regulator.....
 
Sep 26, 2009 at 8:44 PM Post #679 of 2,154
Pin 5 is missing from one of my 4.5V regulator (I can only think of that time where one of the regulators got stuck on my iron tip, or me trying to reflow with C3 in the way and melted the plastic off wiping the pin sideways). As such I can't exactly fix it. I was somehow getting 0.7V out of the 4.5V particular test point, but I couldn't see the output pin. The 3.3V regulator also outputted odd voltage, read about 0.3V but I reflowed the pins on that one and got 3.29V out of that. So, I don't know what happened to the poor regulator, and a new order is heading my way... This paragraph talks about y2's regulators.

What I wanted to do was hardwire y1's 4.5V regulator output (after the cap and ferrite) to y2's 4.5V test point, and cut before the WM8501 supply as to not overload the regulator. I didn't want to go through the hassle so I stopped there.

Edit: massive proofreading
 
Sep 26, 2009 at 11:27 PM Post #682 of 2,154
Hey to all the usb powered people. The computer only sees the pcm2704 right? and PSEL is grounded right? Doesnt that tell the usb to use low power 100ma mode and not 500ma bus power mode if PSEL was high?

If this was the case how would one tell since the gamma 2 sucks more then 100ma? Would simply lifting the pin (well its not a pin but you get the idea) be enough to send it into 500ma bus power mode?


From AMB "The only thing worthy of note is that the PSEL pin, which normally selects self-powered or bus-powered mode, is hardwired to self-powered mode in this circuit. This is because of the fact that we allow on-the-fly switching between the two modes, and that we don't use the PCM2707's built-in 5V-to-3.3V regulator. "
 
Sep 27, 2009 at 12:07 AM Post #683 of 2,154
nightanole, first, it's a PCM2707, not PCM2704. Anyway, the PSEL pin is used as info during USB enumeration so that the host can arbitrate high current devices. Yes, we have it set to low because we also have an external power option. In reality, unless you have a really old computer, you can draw more than 100mA safely (up to 500mA steady state, and even more in short durations). There are plenty of "pseudo-USB" devices (from battery chargers to computer cooling fans, even coffee warmers) that perform no enumeration at all and draw more than 100mA of current.
 
Sep 27, 2009 at 3:31 AM Post #685 of 2,154
I'm not sure if I should post this here or in the y1 thread, but since it is a continuation of the comedy of errors I have been having with my y2 build, I will post this here for continuity.

My y1 is not putting out sound now. Again, I have been using this daily for at least six months, so I know it was a working build. Since my last go round troubleshooting the y2 build, I remated the y1 boards with each other. It is recognized by the computer, power test points check out, switch led goes from red to green with music, but I don't get any output. Previously, it was working fine when mated to the y2. I had also rejoined the y1 boards more than once while working on the y2, and it worked every time. I can only assume that the faulty y2 has harmed the y1 in some way. But in what way?

I had already resigned myself to starting over with the y2 build. But, this is depressing...
 
Sep 27, 2009 at 3:44 AM Post #686 of 2,154
If you're getting data, the switch goes on, 4.5V works, then that would lead to the WM8501 being fried somehow, or the data/clocks not reaching the WM8501. Check and see if optical/coaxial works, and check the mating pins and make sure they're continuous. If you remate the y2 and the y1 makes sound again, it would imply connection problem.
 
Sep 27, 2009 at 2:37 PM Post #688 of 2,154
Quote:

Originally Posted by Beefy /img/forum/go_quote.gif
It might even be something as simple as the output jack is dodgy...?


It's not the jack. Again, the y1 has been my daily use DAC for some time.

Quote:

Originally Posted by ShinyFalcon /img/forum/go_quote.gif
If you're getting data, the switch goes on, 4.5V works, then that would lead to the WM8501 being fried somehow, or the data/clocks not reaching the WM8501. Check and see if optical/coaxial works, and check the mating pins and make sure they're continuous. If you remate the y2 and the y1 makes sound again, it would imply connection problem.


Coax or usb makes no difference. The connection is solid. I guess I will order another WM8501 with the y2 parts. Anyone want to second this plan or suggest other parts?

Edit: Uh, nevermind. I rejoined the y1 to the y2 board and the y1 is outputing music. I guess there was a connection problem. I think I will just leave it connected to the y2 until I get the new y2 parts and board.

Sorry to waste people's time and thanks for indulging my foolishness.
 
Sep 28, 2009 at 12:18 AM Post #689 of 2,154
Ordered the board and other bits form AMB and was disappointed to find that the WM8742GEDS-V is still back ordered at Mouser. Are there any other sources?
 
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