I had previously performed a teardown of the Ciúnas ISO-DAC USB DAC. Since that unit was not working and was bought used, there was some doubt as to how original its construction was. As it turned out, another member had a similar unit, sans the option for USB hub that the other unit had. I already performed a review of that ISO DAC. This is a follow up teardown.
Here is a wide shot of the unit after taking apart the two ends and sliding out the top:
Power comes from the right socket supplied by an external switcher. A switching DC to DC converter at the bottom brings that voltage down to what the LiPoFe battery in blue. Hopefully it is set to the correct charge voltage. There are no electrical protections should the output of that Lithium cell shorts out. The same output that goes to the battery also then powers the electronics.
The main DAC chip is the TI PCM5102 as it was in the other unit I tested. The board next to it is mounted upside down and has some IC on it. Both of these boards are hanging in the air with the only mechanism to keep them from shorting being the stiffness of the wiring. Speaking of those, he should be using stranded wires as solid core wiring can fatigue and break.
The longer board below the two is the Amanero USB interface.
Zooming in on the top two boards we see quite a messy assembly:
Looks like he bought those boards and hand soldered the ICs on them. There is sign of corrosion everywhere that there is soldering. It tells me maybe it is the corrosive flux that was not cleaned after soldering.
No attempt has been made to keep signals separate, making things nice and neat, and reliable.
Focusing on the battery, we see more examples of this:
Notice that the isolation on the battery has either been torn away or melted. Let's hope and pray that what is exposed is the negative terminal of the battery, not positive. As otherwise, it is millimeters from shorting out to that negative tab.
Same corrosion is apparent here.
The biggest puzzler is the power supply:
This is an off-the-shelf LM2596 adjustable switching DC to DC converter. It sells on Amazon for $7 with prime shipping included. That is not the big deal. The big deal is that its output goes to the battery directly and then proceeds to the rest of the electronics. Translating, there is no isolation at all here. Competing products either use relays or FET switches to disconnect the power supply from battery banks. No such thing exists here. As such, call this an "ISO" DAC is just wrong and misleading. No isolation is provided from start (external power supply) to finish (DAC circuits internally).
I don't know if the builder of this product doesn't understand this, or does and still tried to mislead people this way.
Conclusions
This version of ISO DAC is more palatable than the last one because there is less stuffed in it. But otherwise, it is a horrible example of how bad audio electronics can be. There is not one professional engineer that would look at this with anything but disgust. No wonder there are dire warnings in the manual that if you open it, it breaks and voids your warranty. That is wrong. He simply doesn't want you to look a the mess inside this unit.
I had told the owner that I would look to see if I could make it better. But there is just no way to remedy the faults here. Double-stick tape that is used throughout the unit to hold everything from battery to power supply will eventually fail causing these components to come lose to potentially catastrophic end.
The only bit of "good news" is that the cell chemistry used, LifePo4, is quite resilient with respect to abuse. Unlike other chemistry used in EV cars and laptops/tablet/phones, you could short it out, hit it with a hammer and it won't explode due to thermal runaway. It will complain bitterly by outgassing but it is safer technology. They are not used more broadly because their energy density is not as high.
The builder is welcome to come here and explain to us how any of this is acceptable engineering, design and production standards. Until then, my message is simple: please avoid this device. If you have one, I suggest writing to John and asking him if he guarantees the safety of this device in writing. If he does, then maybe you can sell it to others. If it were me, I would take it a recycle place for its battery and write it off as a failed purchase, and not saddle the next owner with it.
--------
As always, questions, comments, corrections, etc. are welcome.
If you like to see more articles like this, please consider donating using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Here is a wide shot of the unit after taking apart the two ends and sliding out the top:
Power comes from the right socket supplied by an external switcher. A switching DC to DC converter at the bottom brings that voltage down to what the LiPoFe battery in blue. Hopefully it is set to the correct charge voltage. There are no electrical protections should the output of that Lithium cell shorts out. The same output that goes to the battery also then powers the electronics.
The main DAC chip is the TI PCM5102 as it was in the other unit I tested. The board next to it is mounted upside down and has some IC on it. Both of these boards are hanging in the air with the only mechanism to keep them from shorting being the stiffness of the wiring. Speaking of those, he should be using stranded wires as solid core wiring can fatigue and break.
The longer board below the two is the Amanero USB interface.
Zooming in on the top two boards we see quite a messy assembly:
Looks like he bought those boards and hand soldered the ICs on them. There is sign of corrosion everywhere that there is soldering. It tells me maybe it is the corrosive flux that was not cleaned after soldering.
No attempt has been made to keep signals separate, making things nice and neat, and reliable.
Focusing on the battery, we see more examples of this:
Notice that the isolation on the battery has either been torn away or melted. Let's hope and pray that what is exposed is the negative terminal of the battery, not positive. As otherwise, it is millimeters from shorting out to that negative tab.
Same corrosion is apparent here.
The biggest puzzler is the power supply:
This is an off-the-shelf LM2596 adjustable switching DC to DC converter. It sells on Amazon for $7 with prime shipping included. That is not the big deal. The big deal is that its output goes to the battery directly and then proceeds to the rest of the electronics. Translating, there is no isolation at all here. Competing products either use relays or FET switches to disconnect the power supply from battery banks. No such thing exists here. As such, call this an "ISO" DAC is just wrong and misleading. No isolation is provided from start (external power supply) to finish (DAC circuits internally).
I don't know if the builder of this product doesn't understand this, or does and still tried to mislead people this way.
Conclusions
This version of ISO DAC is more palatable than the last one because there is less stuffed in it. But otherwise, it is a horrible example of how bad audio electronics can be. There is not one professional engineer that would look at this with anything but disgust. No wonder there are dire warnings in the manual that if you open it, it breaks and voids your warranty. That is wrong. He simply doesn't want you to look a the mess inside this unit.
I had told the owner that I would look to see if I could make it better. But there is just no way to remedy the faults here. Double-stick tape that is used throughout the unit to hold everything from battery to power supply will eventually fail causing these components to come lose to potentially catastrophic end.
The only bit of "good news" is that the cell chemistry used, LifePo4, is quite resilient with respect to abuse. Unlike other chemistry used in EV cars and laptops/tablet/phones, you could short it out, hit it with a hammer and it won't explode due to thermal runaway. It will complain bitterly by outgassing but it is safer technology. They are not used more broadly because their energy density is not as high.
The builder is welcome to come here and explain to us how any of this is acceptable engineering, design and production standards. Until then, my message is simple: please avoid this device. If you have one, I suggest writing to John and asking him if he guarantees the safety of this device in writing. If he does, then maybe you can sell it to others. If it were me, I would take it a recycle place for its battery and write it off as a failed purchase, and not saddle the next owner with it.
--------
As always, questions, comments, corrections, etc. are welcome.
If you like to see more articles like this, please consider donating using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/