Hi, my Curve has a buzz, seems to be a 60cycle type hum, during the first few seconds of every call. I suspected the screen is causing the hum, and it does seem that I can hit the tracball to make the screen light up and the buzz returns during the call until the backlight goes off. Is this normal or should I take the device back? I just got it and have no BB experience before this.
I too suspected it was a grounding or shielding issue with the pulsing of the lighting system for the screen. I looked up the design specs and can see that these are pulsed white LED backlight systems and the brightness circuit simply turns on and off the driver chip at a rate between 100Hz and 1000Hz. The low end of this is exactly what I was hearing.
So basically, the screen brightness is controlled by turing it on and off for different durations, but doing it at a rate of at least 100 times a second so you don't see the flicker.