Dec 13 2013
USB 3D sound card fix
I bought 3 of these USB 3D sound card’s for a wireless music streaming router I am working on.
I plugged one in and it was running in seconds, the first thing I noticed was how bad it sounded then my earphones got hot.
I looked at the voltage output on the left and right channel and saw just over 2v DC on both.
Time to take this thing apart!
What I found was missing DC blocking capacitors. C9 and C20
Note that C9 and C20 have been shorted on the PCB so you need to cut the track . See below.
Now its time to add a capacitor to each side to block the DC voltage.
I used 16v 100uF electrolytic capacitors. This is just what I had to hand and they are small enough so I can close the case back up.
I tested another sound card with a 220uF capacitor and it sounded the same. So anything 100-220uF should work fine.
Note the capacitor polarity. C9 and C20 are marked with + – on the PCB. They are infarct wrong. The + on the capacitor should be connected to – on the PCB.
You can put the capacitors on the top of the PCB and solder on the underside.
That’s it.. Put it back together and test.
No more DC on either channel and it sounds much better.
Done.
tocinow
June 10, 2015 @ 9:34 pm
hi i have one new but i cant use it i dont have the driver
Mick
November 10, 2018 @ 10:04 pm
Windows 7 and up should find the driver online.
TheJuneFire
June 17, 2016 @ 5:46 pm
Do you experience headphones overheating when using this device? After putting these capacitors to use I still got heating problem. It is inconvenient and may be supposed to damage the headphones in long term. Do you have any idea in how to fix it?
Mick
November 10, 2018 @ 10:02 pm
No this fixed the overheating headphones for me. I agree long term heating of the headphones will reduce the lifespan and affect the quality of the audio. As Erich points out in the other comment “We can’t assume that all the polarity data on all the cards is wrong.” You could try reversing the cap.
Tom
November 29, 2016 @ 9:11 pm
Thanks a lot – After 2 days of hunting ground loops and terrible noice on my audio lines, this trick helped to improve the sound quality a lot.
Mick
November 10, 2018 @ 10:05 pm
You are welcome, glad it helped you. Thank you for commenting.
Erich
June 10, 2017 @ 3:33 pm
Hi,
Intriguing! I have burnt out half a dozen of these cheap sound cards. Seems a shame that such a nicely built piece should have such elementary errors. Blast cost cutting!!
Anyway, to my question. Cap polarity. Is there a better way, having cut the ‘shorts’ across the cap points, of determining cap orientation? By measurement! I think I made a mistake with one that nullified the exercise, so i’m about to start over with a new one. We can’t assume that all the polarity data on all the cards is wrong.
Thanks so much, Erich.
If you have used these extensively, have you experienced ‘burn outs’?