AMB Laboratories DIY Audio

[Co60]

I finally got my y2 put together after listening to the y1 for a couple weeks and while it passed all the initial voltage checks, no sound. I checked pin continuity on U4 and U5, re-flowed a couple spots and still nothing. That's when I noticed C11 was reversed "facepalm". After fixing that, still nothing. Did having C11 reversed fry anything? I will try to post some picks later. Thanks.

[helzerr]

I'm assuming you used part number 647-UKW1H220MDD for C11, as the alternative 647-UES1E220MEM is bi-polar.

As 647-UKW1H220MDD is a polarized electrolytic, it could have been damaged by reverse-bias. Simply correcting the polarity may not be sufficient, it probably requires replacement.

You should be able to test if your γ2 is functional by removing C11 altogether. If it works, obtain and install a replacement C11.

[MisterX]

Did having C11 reversed fry anything?

Highly doubtful.

[Co60]

Thanks for the replies. I must have been drinking when I put the y2 together, I noticed that I also placed U6 even though I am using the 8741. I am going to have to go through this with a fine tooth comb to make sure everything else is correct before I move on. One thing I have notice though is that the switch for the y1 stays green when I switch it to optical even though I am only running USB. Any thoughts? Thanks.

[MisterX]

One thing I have notice though is that the switch for the y1 stays green when I switch it to optical even though I am only running USB. Any thoughts?

Check that you have the correct part installed in the U7D position (the TORX module has a black "shutter") and that there are no solder bridges on U2D.

[Co60]

Thanks again MisterX, solved the issue with the y1 switch. Checked everything, re-flowed some suspect spots, but still nothing from the y2. All the initial checks for voltage are normal. I haven't replaced C11 yet, just put it in the right orientation. I will try to post some photos tomorrow.

[amb]

Double check all parts again to make sure you didn't install any other parts backwards.
Did you check/reflow the X1 oscillator? That's a common place where a bad solder joint has caused similar problems with others.

[Co60]

Checked all the chips for continuity and solder bridges and re-flowed any suspects. Here are some shots.

edit: I just noticed after looking at the board layout that C11 was originally correct, C13 was reversed. Both fixed now, should I replace them?

[amb]

edit: I just noticed after looking at the board layout that C11 was originally correct, C13 was reversed. Both fixed now, should I replace them?

I doubt that they've gone bad, but you could try replacing them if you wish.
If you're using WM8741 or WM8742, please remove U6. Although the DAC should still "play" with this error, it's nevertheless not correct.
What part do you have installed in U3?
Measure the DC voltage (relative to ground) at the L+, L-, R+ and R- test pads. Also measure the voltage at the "+" pin of C20 and C26. What do you get?
Does the γ1 analog output work when the γ1/γ2 boards are plugged into each other?

[Co60]

I used the MCP100-315 for U3. U6 has been removed. The R/L test pads measure:

Right = 2.13v both pads
Left = 2.14v Both pads
C20 = 2.17v
C26 = 2.17v

The y1 works when mated with the y2. The only issue I have noticed is that it drops the signal intermittently (the led on the switch goes red)and there is some audible noise when I access the network at the office. This is using the USB input for power and data. This doesn't happen with my computer at home.