AMB Laboratories DIY Audio

[giuliodido]

After several months of perfect functioning, I tried to open the box to verify the grounding of the lateral strips with the case because of "SECOND PROBLEM".

FIRST PROBLEM:
Unfortunately, γ1-γ2 analogical outputs don't work anymore (sometimes, when I carefully bend the boards, I hear distortion sounds or clean music).
In particular, γ1 output doesn't work with S/PDIF RCA and optical inputs. Thus one problem is in the γ1 DAC board. Looking at the schematics, the cause could be cold joints on U2D and/or U3D. But since also γ2 doesn't work, and the connection between γ1 and γ2 boards is ok, the problem is likely to be found in U2D (unless there are further errors in γ2...). Test points are ok.
So I will proceed to reflow U2D.
Am I missing something?

SECOND PROBLEM:
When I turn on the lights or some electronic device in my room, I experience little pauses in the playback: the switch light remain green, but the sound disappear for, lets say, 0.1s. This happens both with USB power (5V) and with wallwart regulated PSU (4.9V). The PSU and the laptop are connected to a filtered APC multiple socket.
What could be the problem?

OFF TOPIC QUESTIONS:
- If I'm not interested in powering the DAC with USB and the USB-to-S/PDIF or USB-to-I²S functions, can I omit the J2U and J3U mating with the γ2 board?

- Is it possible to mate γ1 and γ2 boards without piling one above each other? In this case the connection between the boards will be done with solid core wires, but they will be longer than pin headers. Will this cause any instability in the board? I am talking about 5cm long wires max.


Sorry for this long topic, and thank you in advance.

[lgulyas]

Sometimes I have the same problem(2nd), when I turn on my active monitor speaker my gamma 2 stops singing. I have to reconnect the usb cable to get be the sound back.

[amb]

FIRST PROBLEM:
Unfortunately, γ1-γ2 analogical outputs don't work anymore (sometimes, when I carefully bend the boards, I hear distortion sounds or clean music).
In particular, γ1 output doesn't work with S/PDIF RCA and optical inputs. Thus one problem is in the γ1 DAC board. Looking at the schematics, the cause could be cold joints on U2D and/or U3D. But since also γ2 doesn't work, and the connection between γ1 and γ2 boards is ok, the problem is likely to be found in U2D (unless there are further errors in γ2...). Test points are ok.
So I will proceed to reflow U2D.
Am I missing something?

Definitely sounds like solder joint problems. Does this board have a USB input? If so does it work?
I would definitely reflow all pins on U2D first to see if it fixes the problem. Also perform all voltage checks as described at the websites' "Initial check" sections.

SECOND PROBLEM:
When I turn on the lights or some electronic device in my room, I experience little pauses in the playback: the switch light remain green, but the sound disappear for, lets say, 0.1s. This happens both with USB power (5V) and with wallwart regulated PSU (4.9V). The PSU and the laptop are connected to a filtered APC multiple socket.
What could be the problem?

Poor wiring in the house? Does the problem still happen when the laptop is running on battery?

OFF TOPIC QUESTIONS:
- If I'm not interested in powering the DAC with USB and the USB-to-S/PDIF or USB-to-I²S functions, can I omit the J2U and J3U mating with the γ2 board?

Yes, what you describe is the "S/PDIF-only option" (config E).

- Is it possible to mate γ1 and γ2 boards without piling one above each other? In this case the connection between the boards will be done with solid core wires, but they will be longer than pin headers. Will this cause any instability in the board? I am talking about 5cm long wires max.

Yes, this is how it's done on a γ1 "full++" option (config F). But keep the wire runs short so that the I2S lines are not degraded.

[giuliodido]

FIRST PROBLEM:
Unfortunately, γ1-γ2 analogical outputs don't work anymore (sometimes, when I carefully bend the boards, I hear distortion sounds or clean music).
In particular, γ1 output doesn't work with S/PDIF RCA and optical inputs. Thus one problem is in the γ1 DAC board. Looking at the schematics, the cause could be cold joints on U2D and/or U3D. But since also γ2 doesn't work, and the connection between γ1 and γ2 boards is ok, the problem is likely to be found in U2D (unless there are further errors in γ2...). Test points are ok.
So I will proceed to reflow U2D.
Am I missing something?

Definitely sounds like solder joint problems. Does this board have a USB input? If so does it work?
I would definitely reflow all pins on U2D first to see if it fixes the problem. Also perform all voltage checks as described at the websites' "Initial check" sections.

Yes, it has USB input, but has the same problem of the SPDIF inputs: no output but green light. If the board is bended, output is distortion or clean music.
The fact that the light of the led becomes green (this also happens with SPDIF inputs) maybe suggests that on U2D input pins are ok and the faulty ones are the output's (26-27-28)?

SECOND PROBLEM:
When I turn on the lights or some electronic device in my room, I experience little pauses in the playback: the switch light remain green, but the sound disappear for, lets say, 0.1s. This happens both with USB power (5V) and with wallwart regulated PSU (4.9V). The PSU and the laptop are connected to a filtered APC multiple socket.
What could be the problem?

Poor wiring in the house? Does the problem still happen when the laptop is running on battery?

Yes, even with the laptop running on battery.

[amb]

The fact that the light of the led becomes green (this also happens with SPDIF inputs) maybe suggests that on U2D input pins are ok and the faulty ones are the output's (26-27-28)?

Yes, it seems more like U3D in this case, however not just the output pins, other pins should be checked and reflowed as well.

Yes, even with the laptop running on battery.

Does it also happen when you use the external power supply, a standalone S/PDIF source (e.g., CD player), and leave the USB cable disconnected?

[giuliodido]

Does it also happen when you use the external power supply, a standalone S/PDIF source (e.g., CD player), and leave the USB cable disconnected?

No, for example if I use the optical imput coming from the television (plugged in the same filtered socket) and the DAC is powered with the wallwart, there isn't this problem.

The first problem is now solved: there was a cold joint in U2D; U3D was fine. I also reflowed U1U and checked U4 in γ2, which had a cold joint to the ground.
I strongly recommend to use screwdriver tips instead of sharp tips: my previous solderings were quite bad With a screwdrive tip, solder smd components becomes really easy.

[amb]

Does it also happen when you use the external power supply, a standalone S/PDIF source (e.g., CD player), and leave the USB cable disconnected?

No, for example if I use the optical imput coming from the television (plugged in the same filtered socket) and the DAC is powered with the wallwart, there isn't this problem.

OK, that would suggest a power glitch problem at the laptop computer, not the γ1/γ2...

[lgulyas]

I dont want to start a new topic. I have a similar problem with my gamme except that my gamma stops working when I turn on my speakers and I have to reconnect the usb cable, then it works again. I am using a wallwart to power the gamma 2. The same happens when I turn on my M3. Not all time but it happens really often. It happened in the past few weeks. Any idea?

[amb]

Are all these devices on the same power strip (or even the same wall circuit)? Turning devices on/off is creating enough of a power "brown out" to glitch the laptop's USB port -- weak wall wiring?

[lgulyas]

Everything is on the same wall circuit but it was the same setup earlier. Maybe you are rigth I ll try to connect some of my stuff into other wall circuite.