Turtle Art sensor xo 1.75 range voltage

[forster at ozonline.com.au]

> We should test the calibration again.
Walter, Guzman

Testing with TA140

It looks like the 1.75 audio circuit was changed between the preproduction and the ramp unit 1.75's

Testing on SKU199 and SKU204, the impedance has gone from 1k to 4k and the calibration is all wrong on 204

(TA calibration should be OK for the moment on preproduction SKU199)

Can laptop.org please confirm that there was an audio redesign between SKU199 and SKU204? Is the SKU204 design now stable or can we expect further changes? 

Is the input protection the same as the 1.5: "The XO-1.5 is protected by a resistor,(1/16W 470 ohm SMD0402) and a pair of diodes to ground and to +3.3V which should protect -6V to +9V continuously, and up to higher voltages for shorter periods of time." http://wiki.sugarlabs.org/go/Activities/TurtleArt/Using_Turtle_Art_Sensors#Specifications

Thanks
Tony