01-24-2022, 09:00 AM
(01-24-2022, 07:42 AM)wibble Wrote: We've got the schematic but no gerbers. Look for sw1-c if you want to see what the mic switch is doing, and how you could verify it. It's meant to physically interrupt the bias power to the mic so you could check continuity when the phone's not powered to see if it operates as advertised. That may not be enough to convince you there isn't a sneaky transistor in parallel that can be used to bypass the physical switch though.
I was looking at the schematics regarding the kill switches the other day too and was wondering if cutting the bias would actually prevent the mic from working or just make the input barely audible. Do you know if the bias input is needed for the mic to work at all in the first place?
I have a USB side board which I apparently messed up a bit by trying to resolder the flex cable with the speaker and motor connections. I don't have an explanation what exactly got messed up (I guess something inside the PCB itself because there is no visual damage though that seems strange to me), but one of the symptoms afterwards was barely audible mic input (in addition to a grounded USB data line, also no idea where the ground connection could be located except somehow somewhere inside the PCB). Without removing the mic there are no contact points on which I could check for continuity of the mic bias connection (just the one pin on the connector), but I thought that might be the problem.