Bought a EBay Chinese kit DAC that uses ES Pro processor... And using my kit built PSU...
Soldered in my Burson discrete opamps, and upgraded the single/mono opamps.
Weird issue is I need to flex the pcb to get it to work! So I'm thinking a power issue/circuit trace to the chip, as a signal issue would reveal itself as a channel problem maybe...
Supply seems solid from the input side...
Also, playing music, there is audible distortion in the audio stream. Sounds like it would sound if I removed half the power to the opamps... Only not as bad...? Or line in was too hot..?
I'm seeing full power from my PSU to the Burson's pin 4/8 but on the single opamps, it seems short by a few volts... I don't know if that's by design or an anomaly.
And suggestions appreciated....
Also, reflowed as best I could, solder to some of the SMD components... No improvement.
Soldered in my Burson discrete opamps, and upgraded the single/mono opamps.
Weird issue is I need to flex the pcb to get it to work! So I'm thinking a power issue/circuit trace to the chip, as a signal issue would reveal itself as a channel problem maybe...
Supply seems solid from the input side...
Also, playing music, there is audible distortion in the audio stream. Sounds like it would sound if I removed half the power to the opamps... Only not as bad...? Or line in was too hot..?
I'm seeing full power from my PSU to the Burson's pin 4/8 but on the single opamps, it seems short by a few volts... I don't know if that's by design or an anomaly.
And suggestions appreciated....
Also, reflowed as best I could, solder to some of the SMD components... No improvement.
This is likely a bad via or solder joint, it could be the pcb itself. If both channels are bad,
it's probably power supply related. Doing SMD by hand can make bad joints that look good.
Maybe a heat sink is shorting to a trace underneath it. Measure each supply while flexing the pcb.
A schematic would help, is it this one?
ES9028 ES9028PRO /ES9018 ES9018S Q8 HiFi Audio DAC Decoder DIY KIT | eBay
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A via is a built-in connection between layers, which looks like a smaller pad, and is usually
covered by solder mask. Try pressing around with an insulated tool, or a pencil eraser,
while listening or measuring the voltages.
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I had the Burson's on there from the get go...
Same with my PSU.
The mono opamps came later, but none of these are likely the culprit, AFAIK.
Physical issue for sure, and likely power related.
About the distortion on the output, maybe power related too. I think I should see the same voltage at the single opamps and I do with the duals...?
It appears that all the op amps run off a pair of discrete shunt regulators.
The pcb schematic is the very last photo of the group under the main photo
on the ebay product page.
I had exactly same issue with a new build IGBT audio amp.
I hadn't soldered a joint and it was just touching the via. If I flexed the pcb it crackled in the speaker.
No, the audio output is very "black" and silent in the background... No hum or buzz or static... Just mildly but perceivably distorted.
I think not a short but rather a disconnect...? Like a supply ground lifting or something.
They're shiny on the bottom side, where I soldered them. I'm always concerned about overheating components and maybe that's why the top side looks shitty?
Do these thru-hole solder points attach the component to different planes??
I can reheat the top sides of most of those joints I think....
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