Info about TS472 Aliexpress PCB.

Thread Starter

Qmavam

Joined Nov 6, 2016
10
A question about this was posted 2 years ago and never got a helpful answer. I have this PCB.
https://forum.allaboutcircuits.com/attachments/lonoisepreamp-jpg.213900/
Here is a schematic, but it is only a schematic of the chip and the suggested external components, some of which may be on the pcb.
https://forum.allaboutcircuits.com/attachments/datasheet-pdf.213916/
My starting problem is I attached a small coax to IN+ and IN - labeled A1 and B1 in figure 1 of the pdf. I drove it with my sig gen and it worked.
Then I shorted the jumper labeled VBias, that gives me 2V on the coax to drive my mic. The first thing this tells me is that the Cin+ and CIN- are not present, other wise I could not get DC. But it also make it impossible to hook up according to the schematic.
I also don't understand why the input has GRD, IN+, IN-, and GRD, I connected the mic input coax to IN+ and IN- and don't now what the GRD pins are for. And still have no idea what Vx is.
I think if I trace this board out and make a schematic, it will be the only one, because I find nothing on the internet.
Thanks for any help.
 
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