[Nemo de Monet]

Does anyone here have any experience with the USB sound card kit designed by DIYzone, and frequently available cheap on eBay? It looks like it could be interesting, though probably fairly low-fi. I picked one up a while back, and assembled it, but the thing doesn't work; there's a short somewhere, and I'll be damned if I can figure out where. I've muddled my way through the FAQs in Google-translated gibberish, but they weren't much help. I've gone over every solder joint - twice - and they're all good; I've built SMD stuff - two Mini^3s, two Alien and two Bantam DACs - and countless other projects over the years, so it's not like I'm a total noob at electronics stuff, but this one's got me stumped.

The PCB is very wierd; there's a very, very thick - and opaque - soldermask over everything, on both sides, so you can't see the traces, even when backlit by a bright light.

 

[error401]

Ooops, the site is slloooowwwww and I accidentally double posted.

 

[error401]

Well it looks like there's a proper schematic diagram here if you don't have it already. Elaborate on 'doesn't work'...we need more details to give you anything useful at all. What happens when you plug it in?

The chip this kit uses seems to be one of those lovely undocumented, possibly custom-designed chips. It seems to have a built in 1W (class-D? they mention PWM...) amplifier. It probably sounds quite bad.

 

[Nemo de Monet]

Yeah, I've got the schematic, et cetera. I've narrowed it down to a short on the 3.3v side, but beyond that... can't figure out *why* there's a short. English-language documentation is largely nonexistant, and Google does a really bad job of translating the Chinese discussions, so I was sort of hoping someone here had built one, and perhaps had some experience troubleshooting it. The whole "option" thing gets confusing - "if using option foo, no populate bar", and the board doesn't exactly match the schematic, anyway.

Yeah, one of the things that actually intrigues me the most is the "nonexistent" IC. Ah, well; it was cheap...