dam1021 still broken, no change after downgrading to 1.21FW. The boards apparently "lock on" to I2S signal right after they're powered on but changes back to "unlock" when the Amanero is powered on but not actively transmitting a signal, and it is able to maintain "unlock" when there is no signal even when after the Amanero is powered off. Something must be wrong with the dam1021's digital section. @soekris I think I implemented everything right and the system is fully enclosed in an aluminum box. I was literally just taking off my jacket and putting it on my chair; the dam1021 was 3ft away. This could happen to anyone's Soekris DAC... What am I missing here?
So you loaded: " dam1021 firmware and filters rev 1.21 With new improved anti-aliasing filters, better auto source select and other minor improvements"?
OK - yes you may have broken boards. Send to repair or get new ones. Could happen to anyone - maybe, but it doesn't, so?
I hear in your "tone" that you somehow blame the designer? That's a cul-du-sac - trust me. Just suck it up.
But your fault investigation is not so impressive - you don't seem to want to invest the effort it takes to isolate the fault - more in a sob and blame state...?
You are missing proper shielding or grounding or both.
Chin up mate! Dig in!
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OK - yes you may have broken boards. Send to repair or get new ones. Could happen to anyone - maybe, but it doesn't, so?
I hear in your "tone" that you somehow blame the designer? That's a cul-du-sac - trust me. Just suck it up.
But your fault investigation is not so impressive - you don't seem to want to invest the effort it takes to isolate the fault - more in a sob and blame state...?
You are missing proper shielding or grounding or both.
Chin up mate! Dig in!
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So you broke something due to ESD.... I don't follow what you do and don't, seems like a complex build.... Follow standard debugging procedure, put a scope on the signals, find the broken board and replace it.
The dam1021 is not that easy to break, there is protection on the digital inputs and the power input.... Most broken dam1021 I have seen have been due to experimenting, especially with the power regulators.....
Not actual ESD on the board, but EMI really. I shielded everything but left the dam1021 ground floating (as per small signal systems). I imagine that there must be some protection but I literally had the dam1021 in a grounded metal box 3ft away from where the ESD event occurred. The only thing that could’ve conducted EMI into the dam1021 is the USB cable, fed thru the Amanero.
I can get my hands on a scope, but what would I be looking for? It’s hard to imagine that the SPDIF signal is corrupted (though it could be). It makes more sense for the damage to be on the dam1021 board. Yet the error behavior is complex and I can’t think of why it is. Could it be an isolation chip, or the FPGA? Serial communication works just fine.
If you’re asking me to take everything apart and stare at it, you’re obviously insane. There is no debugging without some kind of hypothesis here. I’ve provided plenty of observations on the fault and it should be enough to identify possible sources of error. For example, you can’t blame the Amanero for corrupting SPDIF when it is literally unpowered. I use reason and logic, and I value my time.
I can say that the only the thing SPDIF and the I2S interfaces have in commonare the 3,3V power supply and the FPGA.... Assuming your sources are known good and the 3.3V line is fine, then you're looking at a dead FPGA, which are too expensive to replace.... On the other hand, both SPDIF and I2S are isolated.....
The 3.3V line is fine as far as I can tell with a multimeter. It's also used to power the SPDIF inputs. The sources should be fine; I've tried several and all had the same symptoms.
I suppose if the FPGA is damaged, it's the section that controls digital input logic? Other board functions seem to be normal, and I can mute the boards too. Also, how could it be damaged by EMI/ESD if it's isolated??? The Amanero had to be the first thing that the overvoltage went through if there was one, as well as other parts on the dam1021. Is the FPGA that brittle?...
I appreciate the help, even if the damaged parts are impossible to replace.
Nvm my deleted message, the 3.3v line is indeed fine!
@soekris Is there any further tests that I can do to more definitively identify the problem? Like I said, the dam1021 and isolated section both have floating grounds (as was suggested in this thread, and elsewhere for small signal electronics, I think); the Amanero is powered by the USB bus, which shares a ground with the isolated section. All the cables are shielded and grounded at one end - the USB cable shield is only grounded at the PC. The entire chassis is grounded. I just don't see how this should've happened. Even if I were to replace the dam1021, I need to make sure that this won't just happen again. I really don't think I did anything wrong or even unusual here.
Edit: I think the dam1021 ground is also connected to the ground prong through a small isolation circuit: a large bridge rectifier, a couple of caps/resistors I think.
@soekris Is there any further tests that I can do to more definitively identify the problem? Like I said, the dam1021 and isolated section both have floating grounds (as was suggested in this thread, and elsewhere for small signal electronics, I think); the Amanero is powered by the USB bus, which shares a ground with the isolated section. All the cables are shielded and grounded at one end - the USB cable shield is only grounded at the PC. The entire chassis is grounded. I just don't see how this should've happened. Even if I were to replace the dam1021, I need to make sure that this won't just happen again. I really don't think I did anything wrong or even unusual here.
Edit: I think the dam1021 ground is also connected to the ground prong through a small isolation circuit: a large bridge rectifier, a couple of caps/resistors I think.
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And the fact that both boards were damaged in pretty much the exact same way at the exact same time... This can't be just chance...
"the Amanero is powered by the USB bus, which shares a ground with the isolated section."
- so not floating! You need to see that the isolated part is feed by power that stem from its own trafo or winding if you really want to separate them. (The terminology bing that the isolated section is behind the, front, non-isolated section)
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- so not floating! You need to see that the isolated part is feed by power that stem from its own trafo or winding if you really want to separate them. (The terminology bing that the isolated section is behind the, front, non-isolated section)
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OK, so not isolated as a ground is shared between the sides via USB - floating or not - whatever you mean buy that.
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What's wrong with you. The grounds are isolated. USB ground is not electrically connected to dam1021 ground.
Yeah, this is getting excruciating to watch.
There is no scenario I can imagine where any part of the DAC being left floating makes sense. Every DAC I've built had lock problems until it was properly grounded. Create a signal ground by connecting the DACs power supply ground to chassis ground through a ground loop breaker. I use a 10R 5W resistor paralleled with a 0.1µF mains-rated cap, I've seen others use a pair antiparallel diodes.
The Amanero, it's power supply, and isolated section of the DAC will all be tied together, and are grounded through the USB cable at the PC.
(Thing is, I swear I can see a resistor/cap ground loop breaker in the photo of the build, so I dunno WTF is going on. But at this point, I'm finding it hard to care.)
Buy a new one. And you can't really expect people to help you for free here with the attitude you are presenting.
I've had success with using the generally recommended method of connecting only the primary side of the PSU with chassis ground and the XLR outputs to ground directly at the outputs. So the only connection between audio ground and chassis is through the PSU. The safety ground goes to the chassis at the PSU inlet. All the dirt (and worse) is kept as far away from the DAC as possible.