Bluetooth module

Al Johnson openmoko at mazikeen.demon.co.uk
Fri Jan 21 11:34:20 CET 2011


On Friday 21 January 2011, Hrabosh wrote:
> Hi guys,
> 
> yesterday I opened my freerunner to check whether mine FR is affected by
> R3004 issue [1].
> 
> It was, I put a piece of wire there instead of those two caps and volume
> got better!
> 
> I have also connected sine wave from generator to the WD8753 mic input
> and cheched it on the WD8753's output with the oscilloscope. It seemes
> that the audio codec chip gets into trouble (distortion, oscillations)
> if the overall audio path has higher gain than 1. I'm going to write
> more about this soon, with the scope pictures included (taken by my
> camera, I don't have DSO at home :-/ )

That would be interesting to see, but your summary seems wrong or perhaps 
oversimplified. Distortion is inevitable if you overload an amp, and 
oscillation isn't unusual immediately after overload. It isn't a function of 
the overall path gain though. The wolfson has a chain of amps and volume 
controls, and it only needs overload at one of them to introduce distortion. 
Stick the gain too high on the first stage (mic input) and the distortion 
won't go away no matter how far you turn down the gain on later stages. This 
has been a long standing problem with the default volume settings.

> But ... when I was dismounting the phone, I dammaged the bluetooth
> module. The module itself may be OK, but the flex cable is torn off.
> 
> Don't you have any idea where can I buy some spare?

I've not seen anyone list them as a spare for sale, but any of the 
distributors might have them available.



More information about the community mailing list