Hello,
I am in need of a DIY person to troubleshoot and repair two Chinese DAC's. The first one is an 1865 NOS DAC that I bought from Aliexpress.. The DAC is cutting out in one channel (left) going from music to distortion to pure noise. Sometimes it sounds like both channels distort but they way the sound goes in and out it is hard to tell. Sometimes the DAC will work for an hour with no issues. But turn it on the next day and the problems return. This problem was intermittent at first but seems to be progressively worse.
The second DAC is a TDA 1387 x 8 DAC I bought on ebay but also a product from China. This DAC has a non working left channel. I can faintly hear some popping and very distorted music from the left channel. The right channel works perfectly.. This DAC was non-working straight out of the box. I am waiting to hear back from the seller on this one
I will of course pay shipping both ways and compensate you for your time and for any needed parts. I do not want to try and send these back to China and pay shipping both ways. That would almost be the cost of the DAC's.
If you are interested you can contact me by pm
I am in need of a DIY person to troubleshoot and repair two Chinese DAC's. The first one is an 1865 NOS DAC that I bought from Aliexpress.. The DAC is cutting out in one channel (left) going from music to distortion to pure noise. Sometimes it sounds like both channels distort but they way the sound goes in and out it is hard to tell. Sometimes the DAC will work for an hour with no issues. But turn it on the next day and the problems return. This problem was intermittent at first but seems to be progressively worse.
The second DAC is a TDA 1387 x 8 DAC I bought on ebay but also a product from China. This DAC has a non working left channel. I can faintly hear some popping and very distorted music from the left channel. The right channel works perfectly.. This DAC was non-working straight out of the box. I am waiting to hear back from the seller on this one
I will of course pay shipping both ways and compensate you for your time and for any needed parts. I do not want to try and send these back to China and pay shipping both ways. That would almost be the cost of the DAC's.
If you are interested you can contact me by pm
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Are you sure this makes financial sense? For the same or less cost, you can buy new DACs
that are likely to be better.
that are likely to be better.
I'd be game to fix these but I'm already in China so probably impractical. Suggest perhaps disassembling the DAC and only sending out the PCB, you'd not want to ship a heavy box and trafo.
The second DAC is likely one of Lee's designs, he's the only guy doing *8 TDA1387s I know of.
As regards better sounding DACs, I'd offer one of my own design as a long time ago I was into modifying Lee Audio's designs to improve the sound and learned quite a bit that way.
The second DAC is likely one of Lee's designs, he's the only guy doing *8 TDA1387s I know of.
As regards better sounding DACs, I'd offer one of my own design as a long time ago I was into modifying Lee Audio's designs to improve the sound and learned quite a bit that way.
Yes mailing them to China defeats the purpose. I do not know how to disassemble the dac's either. Are you going to be back in the US anytime soon?
Not at all likely I'll be in the US anytime, no.
Are you able to open them up and probe them with a multimeter? We could have a try at remote diagnostics.
Are you able to open them up and probe them with a multimeter? We could have a try at remote diagnostics.
Do you have a link to the DACs?
Thats smart not shipping them. They are likely to fail again. Better to use them as a DIY repair experiment and then at worst throw away the boards and use the transformer and case for a recommended build.
Please consider removing your email address. You are making yourself a target for scammers.
I was not sure I was allowed to link to the DAC's.
https://www.aliexpress.com/item/3256801162556002.html
https://www.ebay.com/itm/273149860151
https://www.aliexpress.com/item/3256801162556002.html
https://www.ebay.com/itm/273149860151
The only sensible thing to do is put the dacs for sale in their current condition. This will minimise pain and suffering.
So you have two DACs both with a faulty left channel?
Or do you have two good DACs playing into a faulty system?
The DACs just have four screws to flip the lid. Photos of the boards please.
Or do you have two good DACs playing into a faulty system?
The DACs just have four screws to flip the lid. Photos of the boards please.
Definitely not the system. I replace the defective DAC's with one of my other DACs and everything is fine. I bought the 1865 and the 1387 x 8 DAC's and really liked them. So I bought one more of each. This last pair does not work. I changed headphones, headphone amp, IC cables, digital coax cable and and even switched CD transports and they just do not work with anything.
Bad luck with the last pair of DACs. Weird they both failed on the left.
Flip the lids and post some photos.
Flip the lids and post some photos.
Took of the lids are there is nothing unusual about either DAC to the naked eye. No burn marks. No misaligned parts. No loose wires.. Nothing is loose. I tested both again and the 1865 DAC will distort, go into noise then play. But the DAC only plays for a very short time when it does work (10 seconds) and then works intermittently until fully moving to noise. Again the problem is the left channel.
The 1387 x 8 DAC just has a very low volume mostly distortion signal in the left channel. This DAC was just received yesterday and has never worked correctly.
Someone that can electrically assess the DAC's that has the knowledge and soldering skills to repair them is what is needed.
The 1387 x 8 DAC just has a very low volume mostly distortion signal in the left channel. This DAC was just received yesterday and has never worked correctly.
Someone that can electrically assess the DAC's that has the knowledge and soldering skills to repair them is what is needed.
Hello,
It seems to me that there is a bad connection somewhere - a bad or broken solder joint maybe.
The other option is a bad psu capacitor - that might also cause behaviour like you described.
It might also be something else but these two things come to mind.
Can you take the pcb out and inspect all soldering underside? Use a magnifying glass and check. Google cold solder joint examples to see what you are looking for. It might not be too obvious like a loose contact but you can see that solder didn't quite "stick" to an ic leg or capacitor leg for example.
The least good option is a defective dac ic which you can check if you have spares.
Hope you fix it somehow. 😉
It seems to me that there is a bad connection somewhere - a bad or broken solder joint maybe.
The other option is a bad psu capacitor - that might also cause behaviour like you described.
It might also be something else but these two things come to mind.
Can you take the pcb out and inspect all soldering underside? Use a magnifying glass and check. Google cold solder joint examples to see what you are looking for. It might not be too obvious like a loose contact but you can see that solder didn't quite "stick" to an ic leg or capacitor leg for example.
The least good option is a defective dac ic which you can check if you have spares.
Hope you fix it somehow. 😉
Aha I see now that this is mostly surface mounted and soldered to pcb.
To debug this you need an oscilloscope and datasheets to check voltages and clock signals and so on.
For starters you can as kazap suggested swap left and right opamps and see if the problem remains on the left or is transferred to the right.
To debug this you need an oscilloscope and datasheets to check voltages and clock signals and so on.
For starters you can as kazap suggested swap left and right opamps and see if the problem remains on the left or is transferred to the right.
You must really like the sound on the right channels eh? This seems like throwing good money after bad to me.
That I understand. Can’t imagine servicing them is a value proposition though. Most techs would charge more than they are worth. I would at a minimum want to get the tech to install decent quality power supply capacitors while they are at it, because they are likely of dubious quality, or fake and probably the first things to fail, if they aren’t the problem already.
