I have a USB microphone here that doesn't have a lead. I found an XLR plug and an old USB 4 core lead and assumed I could make my own.
Lower left hand connections appear to be the 5v supply, no problems there (I don't think). The SMT fuse is ok (the microphone is new) and when plugged in, I get 5V at these terminals.
Right hand lower connections I assume to be the signal/data. Minus pin of those two seems to common to ground.
But... when its plugged into the USB port (via a diagnostics USB module), it does not pull any load at all.
Now the third pin on the XLR is the unknown. I would have thought it was the green data lead, but that doesn't do anything.. neither does the white data lead. Which is + and - data I do not know... Google that and you get a varied answer.
The larger chip is an echo processor, so I would have though that would have pulled a small load once the pcb was powered?
Bottom right 8 pin chip is an op-amp I believe.
So... here are my thoughts..
1/ The microphone is broken. Not likely, its new.
2/ The data leads in the USB need some kind of signal/resistance to turn on the microphone? Seems a bit unlikely
3/ The lead should actually be a 6 pin USB. However there are only 3 XLR pins going into the microphone, so you would just have more spare pins.
After trawling around Google, I found an image of the microphone and sure enough... it is an XLR plug that then splits into a USB and a mono 3.5mm.
So, 5v to the left hand side of the pcb, and the XLR screen is the microphone screen. Third XLR pin is the microphone signal.
All working now.
Odd that the unit seems to show zero load on my USB volt/amp monitor. Perhaps its just not a very sensitive monitor